Aprescribed burn is
a. an uncontrolled fire started by humans
b. a controlled fire used to manage forest ecosystems
c. an uncontrolled natural fire
d. a controlled natural fire

The answer is B. a controlled fire used to manage forest ecosystems

Also known as controlled burn or planned burn ( they all the same thing). In Prescribed burning, we burn a specific area in the ecosystems under a specific criteria which actually make the ecosystems better

we usually do this for the following reasons :
-  To maintain biodiversity
- To protect lives in the ecosystems by safely burn a flammable fuel loads
- To rehabilitate vegetation after disturbance

Target heart rate is the answer