Which of the phrases given below the sentence should replace the phrase printed in bold type to make it grammatically correct? If the sentence is correct as it is, mark 'E' as the answer.

We demonstrated to them how we were prepared the artistic patterns.

A.

are prepared

B.

have prepared

C.

are preparing

D.

had prepared

E.

No correction required

Correct answer is D

No explanation has been provided for this answer.