Answer:
D. x(x+5)^2
Explanation:
Factor out an x first and then factor the rest like you normally would
x(x^2+10x+25)
Only factor the inside now. You need two numbers that multiply together to give you 25 and add to get you 10, which is 5.
When factored, it becomes:
x(x+5)(x+5)
(x+5)(x+5) is the same as (x+5)^2