Effector are best describe as
a organ that interpret stimuli
b structures that respond to stimuli
c tissues that initiate stimuli
d four cells that transmit stimuli

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.