He said that he _________ enter the examination room because he was late.
Correct answer: A
Knowledge: modal verb
A. mustn’t + V (bare): not allowed to do anything
B. couldn’t + V (bare): couldn’t do anything
C. needn’t + V (bare): no need to do anything
D. might not + V (bare): can’t do anything
=> He said that he mustn’t enter the examination room because he was late.
(He said that he was not allowed to enter the exam room because he was late.)