[求助]请牛牛们帮我看看这题

....................However,this relation is complicated in intertidal dwellers suc as commuter diatoms by the fact that these organisms are exposed to the solar-day cycle as well as to the tidal cycle, and sometimes display both solar-day and tidal periods in a single behavior. Commuter diatoms, for example, emerge only during those low tides that occur during the day.

前面的主要说commuter diatoms 能根据环境自动调节体内的生物钟。

Which of the followoing can be inferred from the passage about the effect of the solar-day cycle on the tide-associated periodic behavior displayed by commuter diatoms?

A. The solar-day cycle makes this behavior less advantageous to the commuter diatoms ar certain times of the year.

B. The solar-day cycle makes this behavior somewhat more erratic.

C. The solar-day cycle makes this behavior less important to the survivial of the commuter diatoms.

D. Because of the solar-day cycle, this behavior is forced to proceed at a more rapid pace at certain time s during the 24-hour day.

E. Because of the solar-day cycle ,this behavior is not expressed at certain times during the 24 hour day.

这一题为什么要选C

还有什么是solar-day?