N-acetyl muramic acid is found in:
A. Cell wall of plants
B. Cell wall of bacteria
C. Cell wall of fungi
D. Viral coat

Hint:N-acetyl muramic acid is in short known as NAM. The formation of NAM occurs exclusively in the cell cytoplasm. N- acetyl muramic acid is formed as a result of the combination of N-acetyl glucosamine and phosphoenolpyruvate (PEP).

Complete answer:1. The cellulose, non-cellulosic, and pectic polysaccharides, proteins, phenolic compounds, hemicellulose, pectin, lignin, and soluble protein and water are the major components present in the cell wall of plants. So option A is wrong.
2. peptidoglycan also called murein which is made from polysaccharide chains cross-linked by unusual peptides containing D-amino acids are the major components present in the bacterial cell wall. N-acetyl muramic acid is present in the bacterial walls.
3. glucans, chitin, and glycoproteins are the major components of the fungal cell wall. So option C is wrong.
4. A capsid is the protein shell of a virus and is the major component of the viral coat, A capsid encloses the genetic material of the viruses. It consists of many oligomeric (repeating) structural subunits made of a protein called protomers. Therefore option D is also not correct.
Since N-acetyl muramic acid is a major component of bacterial cell wall option (B) is the correct answer.

Note:N-Acetylmuramic acid is commonly known as "NAM" or MurNAc. N-acetyl muramic acid is covalently linked to N-acetylglucosamine and may also be linked through the hydroxyl on carbon number 4 to the carbon of L-alanine.