  Based on the recent breakthrough of Huang (2019), we show that for any total
Boolean function $f$, the deterministic query complexity, $D(f)$, is at most
quartic in the quantum query complexity, $Q(f)$: $D(f) = O(Q(f)^4)$. This
matches the known separation (up to log factors) due to Ambainis, Balodis,
Belovs, Lee, Santha, and Smotrovs (2017). We also use the result to resolve the
quantum analogue of the Aanderaa-Karp-Rosenberg conjecture. We show that if $f$
is a nontrivial monotone graph property of an $n$-vertex graph specified by its
adjacency matrix, then $Q(f) = \Omega(n)$, which is also optimal.
