According to the passage, which of the following is important in explaining a muscle movement（）

单项选择题The sentence He cannot help it (ParA．3, Line l) most probably means （） .

A. man cannot avoid destroying the environment
B. man cannot obtain resources he needs from other planets
C. man cannot survive for a long time
D. man cannot help to create a new environment

单项选择题According to the passage, the development of industry and agriculture seems （）

A．only a burden to the human society
B．the result of the rapid growth of population
C．more harmful than beneficial
D．not likely to slow down