Answer: C — Rational number
$p^2 = \dfrac{32}{50} = \dfrac{16}{25}$, so $p = \pm\dfrac{4}{5}$, which can be written in the form $\dfrac{p}{q}$ ($q \neq 0$), hence p is a rational number.
Simplify 32/50 to 16/25 first, then take the square root to get ±4/5. Since this is expressible as a ratio of two integers with non-zero denominator, it is rational — not irrational. It is not a whole number or integer because 4/5 is a fraction. Examiners expect you to simplify before concluding.