问题详情

According to paragraph 3, what is unusual about the sun"s corona？
A．It is the outmost layer of the sun"s atmosphere and is correspondingly cooler.
B．It is hotter than the photosphere despite being farther away from the core.
C．It is 200 times as deep as the photosphere and is most visible to the naked eye.
D．It is the layer of the sun"s atmosphere where energy escapes as sunlight.请帮忙给出正确答案和分析，谢谢！