Question

Select a suitable option to fill in the blank:

Don't ask Margaret for advice. She ___ know what to do.

• A. can't
• B. couldn't
• C. mustn't
• D. won't

Answer 1

The correct option is D won't

Can't is used to indicate that something is impossible at the present point of time.

Couldn't is used to indicate inability in the past.

Won't is used to indicate the least possibility.

Mustn't is used to indicate prohibition.

Here, the chances of knowing is least for Margaret. So, the correct option is D: won't.