Answer:
The correct answer would be d. stem cells.
The stem cells refer to the undifferentiated cells which have a capability to divide and differentiate into different types of cells.
In addition, they are capable of dividing for self-renewal that is, generation of more numbers of the same type of stem cells.
For example, stem cells in bone marrow give rise to different types of blood cells (RBC, WBC, platelets, NK cells et cetera).
There are mainly two types of stem cells found in human beings; adult stem cells and embryonic stem cells.
