1) Given five consecutive integers, what can be said about the unit digit of their product?

(A) it can be any digit

(B) it can be any even digit

(C) it can be 0 or 5

(D) it is always 0

(E) none of the above.
1) The answer is $\mathbf{( D )}$.

Indeed, among five consecutive integers, at least one is divisible by 5, while at least two are even. Therefore, the product is certainly divisible by 10.