5.

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

Item C/D: The main-slave conjunction as appears at the beginning of the sentence, so the underlined part does not need a conjunction and or a semicolon, and item C/D is wrong.

B item: then means that there is a sequence of actions before and after, according to the meaning of the sentence "When they shifted from the theme of European clocks, the big spire gave way to the shape of the dome tree", there is no sequence relationship, Belong to occur simultaneously, B wrong.