请教高人！谢谢

答案Ａ为什么呢＞＞＞＞？？不大懂啊

Navigators have known for thousands of years that the ocean

has variable currents, but it is only in the last half century that

a reasonably clear picture has emerged of the patterns and

causes of ocean currents.

A.     a reasonably clear picture has emerged of the patterns

and causes of ocean currents.

B.     a reasonably clear picture of the patterns of ocean

currents and their causes have emerged.

C.     a reasonably clear picture emerged of ocean currents,

their patterns and the causes of them

D.     there have emerged a reasonably clear picture of the

patterns of ocean currents and what caused them.

E.      there had emerged a reasonably clear picture of the

patterns of ocean currents and their causes.

subject: picture

predicate: has emerged

object:the patterns and causes of ocean currents

问题是 emerge of这个用法有吗？

而且emerge是不及物动词