困扰很久的两题

12 Emily Dickinson’s garden was a place _____ great inspiration for her poems.
(A) that she drew
(B) by drawing her
(C) from which she drew
(D) drawn from which

15.In the United States, a primary election is a method_____ voters select the nominees for public office
(A) that
(B) is that
(C) by which
(D) by those

困扰很久的两题～为什么都不选A呢？不能看成是同位语从句么？？好不爽啊～