Choose from:
(1). Decibels
(2). hair on head
(3). air pressure
(4). gasoline levels
(5). Acids
(6). energy usage
(7). brain chemistry
(8). blood pH

Fact 1: Blood pH may become unbalanced if the rate of breathing is too fast or too slow. Fact 2: Mammals breathe with lungs. Given the two facts above, what may become unbalanced if the lungs are working too fast or too slow?
Answer:
(8).