You ................................ carry out my instructions immediately. (Command)

Correct option is C

"Must" is appropriate for issuing commands, as it conveys necessity or obligation. The imperative tone of the sentence requires the strong sense of duty expressed by "must."
Information Booster:
1. "Must" expresses compulsion, obligation, or necessity.
2. Frequently used in formal instructions or authoritative contexts.
3. Adds urgency to commands or directives.
4. Different from "may" or "can," which suggest options or possibilities.
Additional Information:
· (a) will: Implies future certainty, not obligation.
· (b) can: Denotes ability, not compulsion.
· (d) may: Indicates permission or possibility, not an order.