Double-helix logic — According to base-pairing rules, the bases on one DNA strand match those on the complementary strand so that the two strands are best described as:

Introduction / Context:
DNA’s double-helical structure features antiparallel strands held together by specific base pairing. The informational content of one strand determines the other, which is why replication is semiconservative and why sequence information can be recovered from either strand in sequencing and cloning work.

Given Data / Assumptions:

• Standard Watson–Crick base pairing: A with T and G with C.
• Strands are antiparallel and not identical in sequence.
• Overall charge arises from the phosphate backbone and is not the defining relational term.

Concept / Approach:
Because bases pair specifically, each base on one strand predicts its partner on the other. This relationship is called “complementarity.” The strands are not identical (one is the complement of the other), and while both carry negative charge due to phosphates, “oppositely charged” is incorrect and irrelevant to sequence matching.

Step-by-Step Solution:

Verification / Alternative check:
DNA polymerases use complementarity to add correct nucleotides during replication, demonstrating the functional reality of complementary strands.

Why Other Options Are Wrong:

• Oppositely charged: both strands are negatively charged; charge is not opposite.
• Identical: sequences are not the same; they are complements.
• None: incorrect since “complementary” is accurate.

Common Pitfalls:
Confusing complementarity with identity; remember antiparallel orientation and base pairing define information complement, not sameness.

Final Answer:
complementary