Researchers combined sequences of fruit-fly DNA from a gene for a particular trait with frog DNA. The mixture was heated to separate the DNA strands. Cooling allowed the single strands to form pairs. The researchers observed that some of the fruit-fly DNA paired with frog DNA. The results provide evidence that___
a. similar nucleotides are present in both fruit-fly and frog DNA
b. fruit flies and frogs can be made to develop some of the same physical traits
c. heat can cause mutations in the DNA sequences of organisms
d. the replication of genetic material can occur at any temperature