Final answer:
A pairs with T, and C pairs with G in DNA due to base pairing. The base-pairing rules state that A will always bind to T, and G will always bind to C.
Step-by-step explanation:
In DNA, A pairs with T, and C pairs with G. This is an example of a specific type of reaction called base pairing. The base pairs A=T and G=C are known as complementary base pairs. The base-pairing rules state that A will always bind to T, and G will always bind to C.
For example, if one DNA strand reads ATGCCAGT, the other strand will be made up of the complementary bases: TACGGTCA.