Adenine and guanine have a fused-ring skeletal structure derived of purine, hence they are called purine bases. ... Similarly, the simple-ring structure of cytosine, uracil, and thymine is derived of pyrimidine, so those three bases are called the pyrimidine bases.
IT'S D becuse none of the other awser choses make sense so ya
ANSWER:I think the answer is number 3
A. They had different types of food. This resulted in many different breeds of finches.
