Why is DNA a useful evolutionary clock?
DNA mutations cause organisms to diverge evolutionarily from one
DNA is the only substance in an organism that never changes.
DNA contains no carbon, so it is not affected by radioactive decay.
DNA decays steadily over time once an organism dies.

The answer is A.

Explanation:

It's "A" because I got it wrong the first time when I put "B" but it was "A".

ans.

gregor john mendel is known for study of inheritance in pea plants. he used garden pea plant for his study, having alternative traits for various characters. he performed cross-breeding in pea plants to check how characters are transmitted between parents to offspring, such as cross between pure tall and pure dwarf plant. mendel studied the inheritance patterns in pea plants for various generations.

thus, the correct answer includes options and f).

c. heat from the poles back down towards the equator.