If each of the four variables represents a nonzero digit, that means each variable must be between 1 and 9, inclusive. Statement (1) is insufficient: any number of combinations will make the product rs greater than the product tu.

Statement (2) is sufficient. While there are an infinite number of solutions to that set of equations, there is only one solution for which all of the variables are integers less than 10: r=6, s=1, t=3, and u=2. Choice (B) is correct.