Which systems act on the same organs but in opposite ways?
a. the central and peripheral nervous systems
b. the sympathetic and parasympathetic nervous systems
c. the somatic and enteric nervous systems

The systems which act on the same organs but both work in opposite ways would be the sympathetic and parasympathetic nervous system - B.

The sympatethic nervous system has often been attributed and called the active nervous system which works when people are being active and awake, while the parasympathetic nervous system kicks in once we're sleeping fo example. 

It would be the equator