Answer:
Adenine, A match-pairs with Thymine, T while Cytosine, C pairs with Guanine, G.
Step-by-step explanation:
Normally, complementary DNA strand obeys Chargaff's rule of base-pairing in 1: 1 ratio, in a scenario with a template strand where a purine pairs with a pyrimidine via hydrogen bonds to create a novel 3-dimensional (3D) DNA structure.
Pyrimidines are normally Cytosine, C and Thymine, T; while Purines are Guanine, G and Adenine, A. So through complementarity, a purine, G must bind a pyrimidine, C and same case for A to T.