Quark composition determines proton structure

Steps:

• Baryons like protons consist of three quarks: up (u, charge +2/3) or down (d, charge -1/3).
• Proton has total charge +1.
• Calculate charge for combinations to match +1.
• Two u and one d: 2*(+2/3) + (-1/3) = +4/3 - 1/3 = +1.

Why B is correct:

• uud provides two up quarks (+4/3 total) and one down quark (-1/3), yielding net charge +1 as defined in the quark model.

Why the others are wrong:

• A: uuu gives charge +2, forming a delta++ baryon, not proton.
• C: udd gives charge 0, forming a neutron.
• D: ddd gives charge -1, forming a delta- baryon.

Final answer: B