Fact 1: Thyroid hormones increase the rate of metabolism in cells throughout the body.

Fact 2: Graves disease is a thyroid gland that overproduces thyroid hormone.

Given the two facts above, answer the question "what increases the rate of metabolism in cells?" with the following options: 
- heat energy
 - heating liquids
 - Smoking
 - adding heat
 - cigarettes
 - smoking cigarettes
 - Graves disease
 - Dehydration


 

       Graves disease  