We're given
The function is continuous for all . If a function is continuous, then
This allows us to pass the limit through the square root:
The limit of a quotient is the quotient of limits (provided the limit of the denominator is not 0):
In the numerator, we can distribute the limit as
So we end up with
Then we just solve for the desired limit:
Obviously the limit can't have two values, so one of these is not right, but only the positive value is one of the answer choices, so the limit is 16.