Fact 1: Hormones control many cell activities, so they are very important for homeostasis.

Fact 2: Growth hormone is an important hormone that declines with aging.

Given the two facts above, answer the question "What affects cell aging?" with the following options: 
- hormones
 - radiation
 - Smoking
 - fat
 - acid
 - temperature
 - cigarettes
 - weather


 

 hormones        