Oxidative cleavage of β-carotene's double bonds yields specific carbonyl products Steps:

• β-Carotene has 11 double bonds (2 in rings, 9 in chain) that cleave to form 9 product molecules: 2 ring-derived tricarbonyls, 4 methylglyoxals, and 3 glyoxals.
• Ring double bond cleavage (C5=C6) plus adjacent chain (C7=C8) yields 2 tricarbonyls: each CH₃C(O)(CH₂)₃C(CH₃)₂C(O)CH=O with 2 ketones.
• Chain cleavages at methyl-substituted doubles (C9=C10, C13=C14 and symmetric) yield 4 methylglyoxals: each O=CHC(O)CH₃ with 1 ketone.
• Unsubstituted chain cleavages yield 3 glyoxals: each O=CHCH=O with no ketones.
• Total products with keto group: 2 tricarbonyls + 4 methylglyoxals = 6.

Why B is correct:

• Complete oxidative cleavage produces exactly 6 fragments bearing at least one ketone, as methyl-substituted double bonds and ring structures generate ketones while others form aldehydes.

Why the others are wrong:

• A: Underestimates; ignores 2 inner methylglyoxals.
• C: Overcounts; includes 3 ketoless glyoxals as having keto groups.
• D: Overcounts; adds nonexistent fragments beyond the 9 total products.

Final answer: B