Which base pair is found in DNA?

Which base pair is found in DNA?

• A. A-A
• B. A-G
• C. A-C
• D. A-T

Answer: (D)

Bases pair in a highly specific way in DNA to keep the double-helix stable. Adenine on one strand pairs with thymine on the opposite strand, forming two hydrogen bonds. This A–T pairing, along with cytosine pairing with guanine (three hydrogen bonds), maintains a uniform helix width and supports accurate replication and transcription. Among the options, the only true DNA base pair is adenine paired with thymine. The other options—adenine with adenine, adenine with guanine, adenine with cytosine—are not the canonical complementary pairs in DNA and would disrupt the proper pairing pattern. (Note: RNA uses adenine pairing with uracil, not thymine.)

Bases pair in a highly specific way in DNA to keep the double-helix stable. Adenine on one strand pairs with thymine on the opposite strand, forming two hydrogen bonds. This A–T pairing, along with cytosine pairing with guanine (three hydrogen bonds), maintains a uniform helix width and supports accurate replication and transcription. Among the options, the only true DNA base pair is adenine paired with thymine. The other options—adenine with adenine, adenine with guanine, adenine with cytosine—are not the canonical complementary pairs in DNA and would disrupt the proper pairing pattern. (Note: RNA uses adenine pairing with uracil, not thymine.)