Until recently historians assumed that calendars with the advent of agriculture.A. came t

问题补充：

Until recently historians assumed that calendars with the advent of agriculture.

A. came to existence

B. came to existing

C. came to exist

D. were existential

答案：

A. came to existence

B. came to existing

(答案→)C. came to exist

D. were existential

解析：考查短语。直到最近，历史学家们认为日历随着农业的出现而存在。come to exist短中to是不定式符号，后面接动词，故选项AB说法有误。选项D描述的是过去的一种状态，选项C描述的是一个动态过程。结合语境可知选C为最佳答案。