Answer and explanation

Correct answer: D. must

  1. Step 1: "Must" expresses a strong obligation.
  2. Step 2: The modal that fits is "must".
Answer
must.
Why not the others: might, can and would do not fit here.

Practise more Writing, Syntax and Language Mechanics.

Free questions with an explanation for every one, and full timed Egyptian Scholastic Test (EST) mock tests.

You wear a seat belt; it is… | Egyptian Scholastic Test (EST)