Answer :
Sentences a, b, c, each have a subject and a verb: that's a good sign that they might be sentences.
Sentence d in contrast does not have a subject. Who ansered the email? we don't know!
it's probably the speaker but it could be anyone
the correct answer is d!
Sentence d in contrast does not have a subject. Who ansered the email? we don't know!
it's probably the speaker but it could be anyone
the correct answer is d!