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

Fact 2: Thyroxine, a thyroid hormone, is an aryl iodide.

Given the two facts above, answer the question "What increases the rate of metabolism in cells throughout the body?" with the following options: 
- Thyroxine
 - Smoking
 - fever
 - bioaerosols
 - acetic acid
 - sweating
 - Power plants
 - heat produced


 

 Thyroxine        