## Core Concept
The question tests understanding of the structural biology of DNA, specifically the type of bond responsible for holding the two strands of DNA together. DNA is a double-stranded helix with sugar and phosphate molecules making up the backbone, and nitrogenous bases projecting inward from the backbone and pairing with each other in a complementary manner.

## Why the Correct Answer is Right
The correct answer, **Hydrogen bonds**, is right because these bonds are responsible for holding the two strands of DNA together. Specifically, adenine (A) pairs with thymine (T) through two hydrogen bonds, and cytosine (C) pairs with guanine (G) through three hydrogen bonds. These interactions are crucial for the stability and replication of DNA.

## Why Each Wrong Option is Incorrect
- **Option A: Covalent bonds** are incorrect because, while covalent bonds are present in the DNA molecule (forming the phosphodiester backbone within each strand), they are not responsible for holding the two strands together.
- **Option B: Ionic bonds** are incorrect because ionic bonds, which involve the transfer of electrons between atoms, are not the primary type of bond holding the DNA strands together.
- **Option D: Peptide bonds** are incorrect because peptide bonds are relevant to protein structure, not DNA structure. They link amino acids together in a polypeptide chain.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the specificity and strength of **hydrogen bonding** between the base pairs are fundamental to DNA's double helix structure and its replication. This is a crucial concept in genetics and molecular biology.

## Correct Answer: C. Hydrogen bonds