Answer:
D
Explanation:
A substitution is where a base is substituted by another base
A. ATGAT - this is not a substitution, the C has been deleted
B. UAGCUA - this is not a substitution, but is the complementary mRNA sequence (you can tell because there are Us instead of Ts)
C. TAGCTA - this is not a substitution, but is the complementary DNA sequence
D. ATGGAT - this is a substitution, the C in the original sequence has been replaced (substituted) by a G.
