Complementary Base Pairing in DNA

Steps:

• DNA with 100 nucleotide pairs is double-stranded, containing 200 nucleotides total.
• Adenine (A) pairs exclusively with thymine (T) in double-stranded DNA.
• The 46 A nucleotides mean 46 T nucleotides pair with them.
• Thus, total T nucleotides equal 46.

Why B is correct:

• Chargaff's rule states that in double-stranded DNA, the number of A bases equals the number of T bases.

Why the others are wrong:

• A: 23 assumes single-strand counting, ignoring the double helix.
• C: 54 miscalculates as 100 minus 46, confusing pairs with bases.
• D: 154 adds unrelated totals, exceeding the 200 nucleotides possible.

Final answer: B