Question

fill in the missing complementary base pair.
dna

Explanation:

In DNA, adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds. This is based on Chargaff's rules and the complementary base - pairing principle in DNA structure.

Answer:

From top to bottom: T, G, C, A.