Identifying biological molecules via specific test reactions

Steps:

• Review the table for color changes or precipitates indicating positive tests for each molecule (e.g., starch with iodine turns blue-black, proteins with biuret turn violet).
• Match solution 1's reactions to standard positive indicators for the target molecule.
• Confirm solution 1 shows unique positive results aligning with one specific test.
• Eliminate solutions 2, 3, 4 lacking those exact indicators.

Why B is correct:

• Option B states "1 only," matching the definition of a positive test where only solution 1 exhibits the characteristic reaction for the molecule, per standard biochemical assays.

Why the others are wrong:

• A includes 2 and 3, but they show negative or mismatched reactions.
• C includes 2 and 4, ignoring solution 1's unique positive indicator.
• D repeats 2 and 4 only, excluding the correct solution 1.

Not enough information: Table details are missing, preventing full verification.

Final answer: B