DNA Base Pairing Rules

Steps:

• Total base pairs = 94, so total bases in double-stranded DNA = 188.
• By Chargaff's rules, adenine (A) pairs with thymine (T), so A = T; cytosine (C) pairs with guanine (G), so C = G.
• Table provides A and C counts in one or both strands; sum A + T + C + G = 188, but A = T and C = G imply total purines (A + G) = total pyrimidines (T + C).
• Guanine total = cytosine total from table (since C = G across both strands).

Why B is correct:

• Matches cytosine count from table, as G equals C in double-stranded DNA per base-pairing rules.

Why the others are wrong:

• A: Underestimates G by ignoring full C pairing.
• C: Overcounts by adding unpaired bases.
• D: Exceeds possible G based on 94 pairs.

Not enough information: Table data not provided.

Final answer: B