Introduction:
Nucleic acids are macromolecules that play a crucial role in the storage, transmission, and expression of genetic information. They are composed of smaller subunits called nucleotides, which are linked together to form a long chain. There are two types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Both DNA and RNA are made up of three main components: a nitrogenous base, a five-carbon sugar, and a phosphate group.

The components of nucleic acids:
1. Nitrogenous base: The nitrogenous base is one of the constituents of nucleic acids. It can be either a purine (adenine or guanine) or a pyrimidine (cytosine, thymine, or uracil). The type of nitrogenous base present in a nucleotide determines whether it is a DNA or RNA molecule. Uracil is a nitrogenous base that is found in RNA but not in DNA.

2. Sugar: The sugar component of nucleic acids is a five-carbon sugar. In DNA, the sugar is called deoxyribose, while in RNA, it is called ribose. The sugar provides the backbone structure for the nucleic acid chain and forms a covalent bond with the phosphate group.

3. Phosphate group: The phosphate group is another constituent of nucleic acids. It consists of a phosphorus atom bonded to four oxygen atoms. The phosphate group is responsible for creating the negative charge of nucleic acids and plays a role in their structure and function.

The incorrect option:
The incorrect option in this case is option B, Guanidine. Guanidine is not a constituent of nucleic acids. Guanidine is a compound that contains a guanidino group (-C(=NH)NH₂) and is not found in the structure of nucleic acids. Guanidine is commonly used in chemistry and biochemistry laboratories as a denaturant and chaotropic agent.

Conclusion:
Nucleic acids are composed of nitrogenous bases, sugars, and phosphate groups. Uracil, phosphoric acid, and ribose sugar are all constituents of nucleic acids, while guanidine is not. Understanding the components of nucleic acids is essential for comprehending their structure and function in biological systems.