What did Chargaff discover while studying bases in the DNA of organisms?
The bases in the DNA of each organism were unique.
The ratios of thymine and adenine were similar, as were the ratios of guanine and cytosine.
The overall percentages of bases were different from one organism to the next.
There were equal amounts of all four bases in every organism, or 25 percent of each base.

The ratios of thymine and adenine were similar, as were the ratios of guanine and cytosine.

Explanation:

Chargaff's Rule:

the correct choice is i and iv.

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.