What is the main topic of the talk

A．Jefferson’s views about commercialized agriculture.

B．International trade in the nineteenth century.

C．Improvements in farm machinery in the United States.

D．Farmers’ loss of independence.

太极拳动作特点是处处带有形，练习时也对身体和心理有要求，正确答案是（）

A.正形体紧注意

B.弧形、体松、心静

C.随意紧张安心