5. Complete the following sentence with a word or words that show a logical relationship.

Question

Joshua took a nap _______ sorting the mail.
A. instead of
B. after
C. while
D. before

I picked D, because we cannot use while, since a person cannot sort mail while sleeping. We cannot use after, because the sentence implies that the first action was done in the past before the second action took place implied by the verbs took and sorting. We cannot use instead of, since the sentence format is not in the past perfect progressive. Is my thinking correct or am I way off?