Answer:
Within double-stranded DNA, the nitrogenous bases on one strand pair with complementary bases along the other strand; in particular, A always pairs with T, and C always pairs with G. Then, during DNA replication, the two strands in the double helix separate.
Step-by-step explanation:
The four nitrogenous bases of DNA are thymine, adenine, guanine, and cytosine. Guanine and cytosine are bound together by three hydrogen bonds; whereas, adenine and thymine are bound together by two hydrogen bonds. This is known as complementary base pairing.