I think the answer is D. A good indicator is the resting heart rate. Exercise strengthen your heart and it makes it more efficient. The resting heart rate shows of the heart is pumping blood normally each time it contracts. Having a normal resting heart rate would mean a healthy heart.
I believe the answer is PREZYGOTIC isolating mechanisms
Answer: FOSSIL
A rock-like copy of a plant,a feather,or a bone(natural things) is a FOSSIL
Explanation: Fossil can be defined as the preserved remains or trace or impression from a plant or animal that pre-existed in history or geological age,these remains are preserved in petrified form in the earth crust.
Fossils serves as the primary source of information about the history of life of a plant or animal on earth.
They are studied by archeologists.
The five types of fossils are; Carbon Fossils,Trace fossils, Body fossils, Molecular fossils and Pseudo fossils.
