Prolonged and constant use of tobacco can weaken the user's immune system and increase the risk of many diseases.. which of the following diseases can makes the air sac in the lungs less elastic, reducing their ability to absorb oxygen? .
a. chronic bronchitis.
b. emphysema.
c. lung cancer.
d. oral cancer.

Melanocytes and keratinocytes work together in protecting the skin from uv damage when keratinocytes a. provide the melanocyte with a protective shield against abrasion b. maintain the appropriate temperature so the product of the melanocyte will not denature c. maintain the appropriate ph in order for the melanocyte to synthesize melanin granules d. accumulate the melanin granules on their superficial portion, forming a uv-blocking pigment layer