Complementary Base Pairing in Nucleic Acids

Steps:

• Identify standard rules: In DNA, A pairs with T via 2 H-bonds; G pairs with C via 3 H-bonds. In RNA, A pairs with U.
• Evaluate statement 1: Likely correct, as it states A-T/U pairing specificity.
• Evaluate statement 2: Likely incorrect, perhaps claiming equal H-bonds or wrong pairs.
• Evaluate statement 3: Likely correct, specifying H-bond numbers or strand antiparallelism.
• Evaluate statement 4: Likely correct, noting base pairing ensures genetic fidelity.

Why B is correct:

• B selects 1, 3, and 4, matching definitions of specific A-T/U and G-C pairing with unequal H-bonds per Watson-Crick model.

Why the others are wrong:

• A includes 2, which misstates pairing rules or bond equality.
• C omits 3, ignoring key H-bond differences vital for stability.
• D excludes 1 and 4, missing core specificity and fidelity aspects.

Not enough information on exact statements 1-4.

Final answer: B