What is best to determine if species are closely related?
A) They have similar physical traits
B) They have similar genetic make up
C) they live in the same geographic area
D) they are easily stackable

I believe the answer is B, it's the most logical.

I hope this helped.

feral cats are estimated to eat tens of millions of native animals each night in australia

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.