Fast!
two numbers have prime factorizations of 2^2 · 3 · 5 and 2 · 3^2 · 7.

which expression can be used to find their least common multiple?

2^3 · 3^3 · 5 · 7
2 · 3
2^2 · 3^2
6 · 2 · 3 · 5 · 7