Answer: The correct answer is-
D: DNA.
DNA replication is a process by which a double stranded DNA molecule produces two molecules of DNA that are identical to each other.
During this process, two strands of DNA are separated and act like a template strand. Using DNA template strand, enzyme DNA polymerase adds dNTPs ( deoxyribonucleoside triphosphate) according to Watson and Crick base pairing ( Adenine pairs with Thymine and Guanine pairs with Cytosine).
Thus, DNA itself is used as template for the process of replication.