In the feedback loop system, the organ or cell that is responsible for carrying out response to a nerve impulse is known as stimulus
Beffector
responder
D receptor

i think its both a and b

it should be d) transitional fossils.

they show the gradualism of evolution throughout a period of time

answer;

c. a tree whose roots are surrounded by wet sand.

explanation;

water stress is an important factor limiting the growth and productivity of forests.water stress is the most often cited cause of poor survival and growth of woody landscape plants.

-insufficient soil moisture is the most common form of water stress, but excess moisture that leads to poor soil aeration (hypoxia) can also result in reduced plant vitality. a tree whose roots are surrounded by wet sand would be least likely to experience water stress.