Differentiate between ‘must’ and ‘have to’ in terms of expressing necessity.

A. Must and have to have the same level of obligation

B. The main difference is that ‘must’ expresses strong necessity or obligation based on the speaker’s opinion or authority, while ‘have to’ expresses external necessity or obligation based on rules, laws, or circumstances.

C. Must is used for external necessity while have to is for internal necessity

D. Must and have to are interchangeable in expressing necessity