Which function is used to read a single character from standard input?

The correct answer is B: getchar(). getchar() reads a single character from standard input (stdin). While fgetc() can also read a character, getchar() is the standard dedicated function for this purpose.

Which of the following correctly represents a structure declaration in C?

The correct answer is C: Both A and B are correct. Both are valid syntax. Option A declares an anonymous structure with immediate variable instantiation. Option B declares a named structure type that can be used later to create variables.

In C, what is the difference between single quotes and double quotes?

The correct answer is B: Single quotes are for characters, double quotes are for strings. In C, single quotes (') are used for single character constants (char type), while double quotes (") are used for string literals (array of characters ending with null terminator).

What is the primary advantage of using INNER JOIN over OUTER JOIN in SQL?

The correct answer is B: It returns only matching records from both tables. INNER JOIN returns only rows that have matching values in both tables, making queries more efficient for specific requirements.

What is the time complexity of searching for an element in an unsorted array using linear search?

The correct answer is C: O(n). Linear search checks each element sequentially. In the worst case, it needs to check all n elements, resulting in O(n) time complexity.