Answer: option A. 
Justification:
By definition the product of the square root of a number times itself is the
same number.
This is:

Because:

Therefore, for the case given:

And you have proved that the product of the two irrational numbers, √11, is a ratonal number, 11.
On the other hand, the other products, B, C, and D do not yield to a rational number. The result of the products shown on B, C, and D are irrational.