Answer
Baryons are made of three quarks or antiquarks, and mesons contain two quarks or antiquarks.
Work Step by Step
Quarks and antiquarks have spin $\frac{1}{2}$, and these can be aligned or anti-aligned.
A combination of 3 quarks and antiquarks gives a spin magnitude of either $\frac{1}{2}$ or $\frac{3}{2}$.
A combination of a quark and an antiquark gives a spin magnitude of either 0 or 1.