Question

The largest collection of coins in England was one of 200,000 silver pennies ________ over 600 years old.

1. A.
   all of which
2. B.
   all of them were
3. C.
   all of them
4. D.
   any of which

Answer 1

C
两个完整的句子之间要有连词（此句中可用and或which，后面部分加系动词），或者用独立主格（C）。