Answer
a. The antineutron contains the quarks $\overline{u}\;\overline{d}\;\overline{d}$.
b. It is not its own antiparticle.
c. Yes, the $\Psi$ is its own antiparticle.
Work Step by Step
a. The antineutron contains the quarks $\overline{u}\;\overline{d}\;\overline{d}$. Each of its quarks is the antiparticle of a corresponding one in the neutron.
b. It is not its own antiparticle, because the 2 possess different quark contents.
c. Yes, the $\Psi$ is its own antiparticle. The antiparticle would have quark content $\overline{c}\;c$, which is the same particle.
