Quark Charges Sum to Zero for Neutral Baryon

Steps:

• Quark electric charges: up (+2/3), down (-1/3), strange (-1/3).
• Down quark charge + strange quark charge = -1/3 -1/3 = -2/3.
• For zero total charge, third quark must contribute +2/3.
• Up quark has charge +2/3, achieving neutrality.

Why A is correct:

• Baryon charge is the sum of constituent quark charges; up quark's +2/3 balances the -2/3 from down and strange to total zero.

Why the others are wrong:

• B. down: Adds -1/3, yielding total charge -1.
• C. strange: Adds -1/3, yielding total charge -1.
• D. anti-strange: Antiquark, not a quark; adds +1/3, yielding total charge -1/3.

Final answer: A