Which statement about the cell membrane is true?

a. it contains cellulose and sugars that are involved in communication.
b. it is present in animal cells only.
c. it is rigid and elastic for supporting the cell’s shape.
d. it prevents harmful substances from entering a cell.

Option D

Explanation:

All cells including that of plants, animals, microorganisms such as bacteria, fungi, algae etc. consists of cell membrane. In-fact some of the internal cell organelles are also bound by membrane.  

Cell membrane is made up of phospholipid bi-layers which consist of two essential components – a) proteins and b) Phospholipids.

This membrane is semi –permeable which means they can allow few substances to pass through it while restricts the passage of others.  

Hence, it protects the cell from harmful substance in its surrounding.  

Thus, option D is correct.

Thus, option D is correct.

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.