Semiconservative DNA replication conserves one original strand per new molecule

Steps:

• Recall that semiconservative replication, proven by Meselson-Stahl experiment, means each new DNA double helix has one parental strand and one newly synthesized strand.
• Evaluate choices against this: A and B misstate conservation as "half," C ignores both strands as templates, D matches the one original strand as template.
• Confirm D aligns with Watson-Crick model where each parental strand serves as a full template for a new complementary strand.
• Select D as it precisely explains the "semi" (half conserved) aspect.

Why D is correct:

• Semiconservative replication is defined as each new DNA molecule using one complete original strand as the template, conserving half the original duplex.

Why the others are wrong:

• A: Entire original strands are conserved, not just half of each.
• B: The full base sequence of each original strand is conserved, not half.
• C: Both strands of the original DNA serve as templates, not just one.

Final answer: D