The correct option is D Acetyl glucosamine
Chitin is a complex homopolysaccharide and second most abundant organic substance. It is found as the structural component of fungal walls and also called fungal cellulose. It is soft and leathery and provides strength and elasticity. Chitin is a homopolymer of N-acetyl glucosamine residues which are linked together by β1-4 linkage. Thus, the correct answer is B.