Answer:
Shock, age and climate.
Explanation:
The processes that may cause the leaves to drop and fall are shock, age and climate. The plants drop their leaves due to shock when they experience by transplanting from place to another. When the leaves get older having yellow colour so due to no function it falls. The climatic condition is also responsible for the dropping of leaves. Those plants which can't grow in cool season so when the winter comes they shed their leaves and wait for the summer season.
The answer of the question is A
A toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
I think the answer is a cell..
