Quark charges sum to hadron charge

Steps:

• Quarks have fractional charges: up (u) +2/3 e, down/strange (d/s) -1/3 e.
• For a three-quark baryon with total charge -e, sum of quark charges = -1.
• Three u quarks: +2/3 × 3 = +2 (not -1).
• Two u, one d/s: +2/3 + 2/3 -1/3 = +1 (not -1).
• One u, two d/s: +2/3 -1/3 -1/3 = 0 (not -1).
• Three d/s: -1/3 × 3 = -1 (matches).

Why A is correct:

• Option A (sss) gives three strange quarks, each -1/3 e, totaling -e per the additive charge rule for baryons.

Why the others are wrong:

• B (uuu): Total charge +2e, exceeds -e.
• C (uud): Total charge +e, positive not negative.
• D (udd): Total charge 0, neutral not charged.

Final answer: A