A student analyzed a double-stranded DNA molecule and found out that the DNA has 19% C. Determine the percentages of G, A, and T. Explain.

• A. If the DNA sample has 19% C, then it should have 19% A, since C and A are complementary. The sample also contains 31% T and 31% G, since T and G are also complementary.
• B. If the DNA sample has 19% C, then it should have 19% T, since C and T are complementary. The sample also contains 62% A and % 62G, since A and G are also complementary.
• C. If the DNA sample has 19% C, then it should have 19% G, since C and G are complementary. The sample also contains 62% A and 62% T, since A and T are also complementary.
• D. If the DNA sample has 19% C, then it should have 19% G, since C and G are complementary. The sample also contains 31% A and 31% T, since A and T are also complementary.

Answer: (D)