Final answer:
Biological evolution is based on changes in a population's genetic makeup over time and the ability of individuals to adapt.
Step-by-step explanation:
Biological evolution is based on changes in a population's genetic makeup over time (II) and the ability of individuals to adapt (I). Changes in the traits of an individual (III) are not the primary basis of biological evolution.
Evolution is the change in genetic composition of a population over generations, resulting from differential reproduction of individuals with certain alleles. Natural selection acts on individuals with advantageous traits, allowing them to survive and reproduce, leading to changes in the population's genetic makeup over time.
Therefore, the correct answer is A. I and II only.