Antiparticles have opposite electric charges to their corresponding particles

Steps:

• The top quark is an up-type quark with electric charge +2/3 e.
• Antiparticles carry the opposite charge of their particle counterparts.
• Therefore, the anti-top quark has charge -(+2/3 e) = -2/3 e.
• This follows the standard model of particle physics, where charge is conserved in particle-antiparticle pairs.

Why A is correct:

• By definition, the antiparticle of the top quark (charge +2/3 e) inverts the sign, yielding -2/3 e.

Why the others are wrong:

• B: Matches the charge of an anti-down quark (-1/3 e), not anti-top.
• C: Matches the charge of a down quark (+1/3 e opposite), not anti-top.
• D: Matches the charge of the top quark itself (+2/3 e), not its antiparticle.

Final answer: A