theory predicts how and when we detect the presence of a faint stimulus. Assumes that there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and level of fatigue.

Signal detection theory

Explanation:

Signal detection theory predicts the relationship of how well a signal is detected and the psychological state of the observer. This theory evaluates how and when the presence of a faint stimulus ("signal") amid background stimulation ("noise") is detected. Assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and level of fatigue

hormones in blood stream

image: dtc.ucsf.edu

endocrine glands secrete hormones into the blood stream near them; the hormones then travel in our bloodstream until it reaches its destination, called a target cell, in distance parts of the body. in the target tissue, hormones lock onto the target’s plasma membrane, called the receptor site.

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.