Final answer:
Growth is the process that leads to an organism's increase in mass through the formation of new cells, new non-cellular material, and sometimes the enlargement of existing cells. Hence the correct option is D.
Step-by-step explanation:
The process that results in mass being added to an organism, which may include the formation of new cells and new structures, is called growth. Hence the correct option is D.
Growth is an increase in size that occurs when there's a higher rate of anabolism than catabolism. This process includes the creation of new cells, an increase in non-cellular material, and in some cases, an increase in the size of existing cells. During growth, humans, as with other multicellular organisms, accumulate mass not only by increasing the number of cells through the process whereby new cells are formed to replace worn-out cells but also by adding non-cellular substances such as mineral deposits in bones.