Using the $(n + l)$ rule: For 4d, $n=4, l=2, n+l=6$. For 5p, $n=5, l=1, n+l=6$. For 5f, $n=5, l=3, n+l=8$. For 6p, $n=6, l=1, n+l=7$. Comparing $(n+l)$ values: $5f(8) > 6p(7) > 4d(6) = 5p(6)$. Since 4d and 5p have the same $(n+l)$, the one with higher $n$ has higher energy, so $5p > 4d$. Thus, the order is $5f > 6p > 5p > 4d$.