Hey there!
I want you to think of radicals as like terms. In order to be able to combine like terms, you need the same base and exponent.
For example,
3x^2-y^2 <== same exponent but not same variable
3x^2-x^2 <=== could be combined because exponent (^2) and variable (x) are the same
So, for this question, you're looking for a radical that has 5 under the radical sign and 3 above the radical sign.
"B" is the right answer, because is ∛ and in the radical it has a √5.
I hope this helps!
~kaikers