**Core Concept**
DNA (Deoxyribonucleic acid) is a double-stranded helix composed of nucleotides, each containing a sugar molecule (deoxyribose), a phosphate group, and one of four nitrogenous bases - adenine (A), guanine (G), cytosine (C), and thymine (T). The sequence of these nitrogenous bases determines the genetic information encoded in DNA.

**Why the Correct Answer is Right**
The correct answer is deoxyribonucleic acid because it is the primary molecule responsible for carrying and transmitting genetic information from one generation to the next. DNA replication involves unwinding the double helix, synthesizing new complementary strands, and re-forming the double helix. This process relies on the base pairing rules: adenine pairs with thymine, and guanine pairs with cytosine, ensuring the accurate transmission of genetic information.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct component of DNA. While nucleotides are a component of DNA, the question asks for the major component, which is the DNA molecule itself.
**Option B:** This option is incorrect because it is a component of DNA, but not the major component. Deoxyribose is a sugar molecule found in each nucleotide, but it is not the overall structure of DNA.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that DNA replication is semi-conservative, meaning that one parent strand and one newly synthesized strand are present in the resulting DNA double helix.

**Correct Answer: A. Deoxyribonucleic acid**