In an attempt to attract more tourists, [the Swiss government commissioned
several life-size fiberglass cow statues, having them decorated by local
artists, and] set them up on the streets of Zurich.
A the Swiss government commissioned several life-size fiberglass cow statues,
having them decorated by local artists, and
B the Swiss government commissioned several life-size fiberglass cow statues,
they were decorated by local artists, and then
C the Swiss government commissioned several life-size fiberglass cow statues,
had them decorated by local artists, and
D several life-size fiberglass cow statues were commissioned by the Swiss
government, decorated by local artists, and then
E several life-size fiberglass cow statues, commissioned by the Swiss
government, were decorated by local artists, and they
我的答案选B，正确答案是C。想请问原因是?
谢谢