**Core Concept**
The question focuses on the chemical structure of the four nucleotide bases found in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). Specifically, it highlights the unique covalent bonds that hold these bases together in the double helix structure of DNA.

**Why the Correct Answer is Right**
In the DNA double helix, cytosine (C) forms a triple hydrogen bond with guanine (G), while adenine (A) pairs with thymine (T) through double hydrogen bonds. This specific base pairing is crucial for the stability and replication of DNA. The triple hydrogen bond between C and G is due to the unique arrangement of their molecular structures, which allows for the formation of three hydrogen bonds between the nitrogenous bases.

**Why Each Wrong Option is Incorrect**
**Option A:** A-T base pairs do not form triple bonds; instead, they are held together by two hydrogen bonds, which is insufficient for the stability of the DNA double helix.
**Option C:** A-G base pairs are not found in the standard Watson-Crick model of DNA, as adenine and guanine are not complementary bases.
**Option D:** C-T base pairs are not known to form triple bonds; the base pairing between cytosine and thymine is typically characterized by two hydrogen bonds.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the base pairing rules in DNA are crucial for its replication and repair. The unique chemical properties of adenine, thymine, cytosine, and guanine allow for the precise pairing of these bases, which is vital for maintaining the integrity of genetic information.

**Correct Answer:** **✓ Correct Answer: B. C-G**