Fehling's test positive for primary alcohols via oxidation to aldehydes Steps:

• Identify all structural isomers of C4H10O: four alcohols (butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol) and three ethers.
• Ethers do not react with Fehling's solution, as they lack oxidizable groups.
• Among alcohols, only primary ones oxidize to aldehydes, which reduce Cu²⁺ to red Cu₂O precipitate.
• Primary alcohols are butan-1-ol (CH₃CH₂CH₂CH₂OH) and 2-methylpropan-1-ol ((CH₃)₂CHCH₂OH); secondary (butan-2-ol) forms ketone, tertiary (2-methylpropan-2-ol) does not oxidize.

Why B is correct:

• Exactly two primary alcohols can be oxidized to aldehydes that give the red precipitate, per the test's mechanism for reducing agents.

Why the others are wrong:

• A: Underestimates; misses the second primary alcohol.
• C: Overestimates; might include the secondary alcohol, but ketones do not reduce Fehling's.
• D: Overestimates; includes all four alcohols, but secondary and tertiary do not give the test.

Final answer: B