Which nitrogen base sequence is the partner of C–A–T–C–G–A?

In DNA, cytosine pairs with guanine (C–G), and adenine pairs with thymine (A–T). Match each base in C–A–T–C–G–A to its partner: G–T–A–G–C–T. Therefore, the partner sequence is G–T–A–G–C–T, choice B.

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