Answer:
A. is correct
Explanation:
sqrt3*sqrt12 can be rewritten as √3·√12, which can be extended to
√3·√3·√4.
Note that √4 = 2 and that (√3)^2 = 3,
so the final result is 2*3, or 6 (a rational number).
A. is correct: √3 and √12 are both irrational, but their product is rational.