Concept:
Streptomycin is an aminoglycoside antibiotic. Its molecule is made by joining three sugar-like pieces together.
Step 1:
The three building blocks of streptomycin are: streptidine, streptose, and N-methyl-L-glucosamine. All three are present, not just two of them.
Step 2:
So any option that lists only two pieces (Options 1, 2 and 3) is incomplete. The full and correct answer must name all three components.
Answer: Option (4) — Streptidine, streptose and N-methyl-L-glucosamine.