Both options A (positional parameter) and B (named parameter) correctly use PDO prepared statements, which separate SQL logic from data, thereby preventing SQL injection. Option C uses `query()` and string concatenation with `quote()`, which is less secure and idiomatic than prepared statements and does not fully leverage PDO’s protection mechanisms.

When `json_decode()` fails to decode a string, it returns `NULL`. However, `NULL` is also a valid return for the JSON string “null”. Therefore, the correct way to detect a parsing error is to use `json_last_error()`, which will return `JSON_ERROR_NONE` if no error occurred. Relying solely on the return value being `NULL` is not sufficient for robust error handling.

The `insteadof` operator is used to resolve conflicts by explicitly choosing which trait’s method to use over another. The `as` operator can be used to alias a method name to resolve conflicts, but it does not exclude a method; it renames it. PHP does not have `override` or `exclude` keywords in the context of trait conflict resolution.

To create a custom session save handler, a class must implement the `SessionHandlerInterface`. This interface defines the core methods like `open()`, `close()`, `read()`, `write()`, `destroy()`, and `gc()` that PHP’s session management logic will call. The other options are not valid core PHP interfaces or classes for this purpose.

`array_map()` applies the `intval` function to every element in the `$_POST[‘numbers’]` array. The primary purpose is type casting/juggling: it forces each value to be an integer (e.g., the string “123” becomes the integer 123). This is a form of input filtering that ensures consistent data types for later arithmetic or comparison operations. It is not a robust validator, as `intval(‘abc’)` returns 0, nor does it escape data for SQL.

Using `fopen()` with `fgetcsv()` in a loop is the classic, memory-efficient pattern because it reads the file one line at a time into a buffer, rather than loading the entire file into memory. Option D using `SplFileObject` is also very good and object-oriented, but the question asks for the most memory-efficient, and the core `fopen`/`fgetcsv` combination is the fundamental low-level approach. Options A and C load the entire file contents at once, which is inefficient for large files.

PSR-4 specifies that the namespace separators (`\`) are converted to directory separators (e.g., `/` on Unix). The class name case must be preserved. Therefore, the correct replacement is `str_replace(‘\\’, DIRECTORY_SEPARATOR, $relativeClass)`. Using `DIRECTORY_SEPARATOR` makes the code portable across different operating systems. Option A is almost correct but hardcodes the `/` separator. Option B is wrong as it doesn’t replace the namespace separator. Option C is wrong because it changes the case.

In PHP, variables from the parent scope are imported into the closure’s scope using the `use` language construct. By default, they are imported by value. This means the closure receives a copy of the variable’s content at the time the closure is defined. To import by reference (so changes inside and outside the closure affect the same variable), an ampersand (`&`) is required, as in option B. Options C and D are for different variable scoping mechanisms.

An abstract class is used to provide a common base definition while preventing it from being instantiated directly. An abstract method within it (declared with the `abstract` keyword) forces any concrete child class (like `FileLogger`) to provide a specific implementation. An interface (Option C) also enforces a method signature but cannot contain any implementation code. Option B is a poor pattern known as the “Template Method” pattern done incorrectly, as it relies on runtime errors rather than compile-time enforcement. Option D (a trait) is for code reuse, not for defining a contract.

Both options A (positional parameter) and B (named parameter) correctly use PDO prepared statements, which separate SQL logic from data, thereby preventing SQL injection. Option C uses `query()` and string concatenation with `quote()`, which is less secure and idiomatic than prepared statements and does not fully leverage PDO’s protection mechanisms.0