Answer:
a. 4.33.
Explanation:
If there is only one correct answer out of four alternatives, the expected proportion of correct answers is p =0.25
Sample size (n) = 100 questions
The standard deviation of a proportion 'p' is given by:

Applying the given data:

If X is the number of correct responses in 100 guesses, the standard deviation of X is:

The standard deviation of X is 4.33 questions.