Final answer:
The DNA sequence from the options provided most likely to melt and initiate replication would have the highest A-T content. The sequence given GCTTATAT would be complementary to c. CGAATATA, following the base pairing rules where A pairs with T and C pairs with G.
Step-by-step explanation:
In DNA replication, DNA strands are complementary and antiparallel. This means that each base on one strand pairs with a specific counterpart on the other: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). When predicting the 13-mer DNA sequence that initiates DNA replication, also known as the origin of replication, you'd typically look for a region rich in A-T pairs because A-T pairs have two hydrogen bonds, compared to the three hydrogen bonds in G-C pairs, making them easier to separate.
Given this information, the sequence most likely to melt to initiate DNA replication would be one with the highest A-T content. The sequence that would be complementary to GCTTATAT is c. CGAATATA, as it follows the base pairing rules discussed.