2.
Pick the answer that completes the blank/s in the best, most suitable and accurate English.
'If they got out of London before the worst of the rush-hour, the earliest they ... ... 7:45 or so.'
... could of arrived here for supper would be ...
... would have arrived here for supper could be ...
... could arrive here for supper would be ...
... could arrive here for supper is ...
The plain present (Answer 1) would be understood but isn't natural here; Answer 3 is possible but, again, somehow slightly less natural in context; despite 'last' suggesting something being past or finished, the past tense in Answer 4 is also wrong here.