It is correct "... you must wear ..."?

[Jon]

English Grammar Tests, Elementary Level

ESL/EFL Test #50 "Elementary Grammar Questions", question 10

It is a rule: if you ride in my car you ......... wear your seatbelt.

(a) may
(b) might
(c) can
(d) have to

English Grammar Tests, Elementary Level

ESL/EFL Test #50 "Elementary Grammar Questions", answer 10

It is a rule: if you ride in my car you have to wear your seatbelt.

Correct answer: (d) have to
_________________________

It is correct "... you must wear ..." ??

Thanks in advance!!

Jon

[Mister Micawber]

.
Yes, you could also use 'must' here.
.
_________________
Native English teacher at Mister Micawber's

[Saobang972]

But I think might is also the correct answer, as my knowledge that "Have to" and "migh" are same meaning in positive sentences.
Can you explain to me ??

[Mister Micawber]

No, your knowledge is confused: 'have to' is necessity and 'might' is possibility.
_________________
Native English teacher at Mister Micawber's

[Saobang972]

yeb "Mister Micawber"
I'm confused between might and must. Thank for your remind :D