Should (follow-up questions)

[Rustamsher]

Dear Alan. Please have a look at the following tests:

1) Jack arrived without his wallet. He ... have lost it in his business trip.

a) could
b) should
c) would
d) will

In my humple opinion, both (a) and (b) are grammatical, but (b) is the most appropriate answer. Am I right?

2) When did the burglary happen?

a) It could have happened during the night.
b) It may have happened while she was at work.
c) It should have happened while she was with her friends.
d) It have happened when she was at the cinema.

Is C the intended answer?

Many thanks.

[Alan]

1. Only (a) makes sense. (N.B. 'on' not 'in' his business trip)
2. Only (a) and (b) make sense.