Solution:
Root hair cells are specialized epidermal cells that greatly increase the surface area of roots. The function of root hairs is to collect water and mineral nutrients present in the soil and take this solution up through the roots to the rest of the plant.

Solution:
Radish is a modified root.

Solution:
Vitamin D is the sunshine vitamin that has been produced on this earth for more than 500 million years. During exposure to sunlight 7-dehydrocholesterol in the skin absorbs UV B radiation and is converted to previtamin D3 which in turn isomerizes into vitamin D3.

Solution:
Dermatology is the branch of science which deals with the study of skin.

Solution:
Photosynthesis takes place in the presence of chlorophyll and sunlight.

Solution:
Human red blood cells (RBC), after differentiating from erythroblasts in the bone marrow, are released into the blood and survive in the circulation for approximately 120 days. In humans and some other species, RBC normally survive in a nonrandom manner.

Solution:
The humerus is the long bone in the upper arm. It is located between the elbow joint and the shoulder. So, the correct option is C.