GWD-5的一道语法题

GMAT760!!

Unlike theoriginal National Museum of Science and Technology in Italy, wherethe models are encased in glass or operated only by staff members, the VirtualLeonardo Project, an online version of the museum, encourages visitors to“touch” each exhibit, which thereby activates the animated functions ofthe piece.

A.    exhibit, which thereby activates

B.    exhibit, in turn an activation of

C.    exhibit, and it will activate

D.   exhibit and thereby activate

E.    exhibit which, as a result, activates

正确答案是选D，但我不知道为什么不用单数，因为我看如果平行也是和encourages平行

Monica2020

不啊，平行如果和encourage的话，activate的主语就会变成the VirtualLeonardo Project。
activate是和touch平行
摘自beattheGMAT的原话：
“By using the word "and," the sentence is clearly showing that the visitors are doing 2 actions: touch the exhibit and activate the animated functions. Both actions are worded using parallel structure by using singular verbs (touch/activate).”