The entropy of a system measures the state of disorder of the system.

The right answer is true.

The term entropy was introduced in 1865 by Rudolf Clausius from a Greek word meaning "transformation". It characterizes the degree of disorganization, or unpredictability of the information content of a system.

For example, in physics, entropy is a thermodynamic quantity associated with a particle system. In astrophysics, the entropy of black holes has been introduced. And in statistical physics: entropy of a gas of bosons, fermionic entropy.

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.

to this one it would be receptive field