What drives the pairing of free-floating nucleotides during DNA replication?

The process of pairing free-floating nucleotides during DNA replication is primarily driven by the base pairing rules. These rules, which dictate that adenine pairs with thymine and cytosine pairs with guanine, are fundamental to the structure of DNA. During replication, free nucleotides in the nucleus align themselves with their complementary bases on the existing template strand of the DNA. This complementary base pairing ensures the newly synthesized strand is an exact copy of the original strand.

While DNA polymerase does play a critical role in synthesizing the new DNA strand by adding these nucleotides, the actual driving force behind the specific pairing of the nucleotides is the established relationships dictated by the base pairing rules. Base pairing relies on the specific hydrogen bonding capabilities of the nitrogenous bases, ensuring that the new strand is complementary to the template strand. Therefore, the accurate pairing of nucleotides follows the base pairing principles, making the base pairing rules the correct answer.