How to use must in a sentence

Must is a verb, so you must use it with an action. The subject must do an action for the word to be used correctly, or to be told to do an action.

For example:

John must complete his homework before he can go out and play.

You must complete all tasks to win the prize money.

To use must correctly there must be a desired goal, but an obstacle between where the person is now and their goal.

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fiction/fantasy

explanation:

the answer is c because info security should not use them for code