Quark charges determine baryon electric charge

Steps:

• Up quark charge: +2/3 e; down and strange: -1/3 e (e = 1.6 × 10^{-19} C).
• Baryon charge = sum of three quark charges.
• Proton charge = +1 e; calculate each option's total.
• Identify combination not equaling +1 e.

Why D is correct:

• Three up quarks: +2/3 e + 2/3 e + 2/3 e = +2 e (delta++ baryon, charge +2 e by quark model).

Why the others are wrong:

• A: Up + down + down = +2/3 -1/3 -1/3 = 0 e (neutron).
• B: Up + strange + strange = +2/3 -1/3 -1/3 = 0 e (neutral hyperon).
• C: Up + up + down = +2/3 +2/3 -1/3 = +1 e (proton).

Final answer: D