A solution that maintains its ph within a narrow range is called a buffers.
'The endocrine system<span> is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs. These hormones regulate the body's growth, metabolism (the physical and chemical processes of the body), and sexual development and </span>function' According to Google.
This would be an example of:
C) an insertion mutation.
Notice how the sequence contains the same letters as before, only an A is added to the beginning. Adding extra nucleotides is an example of an insertion mutation, a type of frame-shift also, because the reading frame will be thrown off downstream.