Which of the following describes complementary base pairing in DNA?

• A. $A$denine pairs with $C$ytosine, and $G$uanine pairs with $T$hymine.
• B. $A$denine pairs with $T$hymine, and $C$ytosine pairs with $G$uanine.
• C. $T$hymine pairs with $G$uanine, and $A$denine pairs with $C$ytosine.
• D. $C$ytosine pairs with $T$hymine, and $A$denine pairs with $G$uanine.

Answer: (B)

Verified step by step guidance

1. Understand the concept of complementary base pairing in DNA, which is crucial for the structure and function of DNA molecules.
2. Recall that DNA is composed of two strands forming a double helix, where the bases on one strand pair with the bases on the opposite strand.
3. Identify the specific base pairing rules: Adenine (A) pairs with Thymine (T) through two hydrogen bonds, and Cytosine (C) pairs with Guanine (G) through three hydrogen bonds.
4. Evaluate each option given in the problem to determine which one correctly follows the base pairing rules.
5. Select the option that states 'Adenine pairs with thymine, and cytosine pairs with guanine' as it correctly describes the complementary base pairing in DNA.