Which best describes the effect negative incentives have on a certain course of action?
a. they make the action impossible.
b. they make the action less profitable.
c. they make the action difficult.
d. they make the action less likely.

explanation:

a gas is not used in hydraulic machines as the fluid because gas is easily compressible and so if a gas is used, the energy would mostly go into compressing a gas. therefore a liquid is used in hydraulic machines as the fluid.