7. What is the main idea of the third paragraph?
a. Rotten apple can be very bad fruit for skin cell.
b. People call the aging skin cell “rotten apple”.
c. Skin cell are involved in repairing wounds and be able to maintain their ability to
Divide.
cl. Skin cell can be used as “rotten apple" to help the neurons.
e. Aging skin cell can damage the nearby cells.