In terms of notation "sqrt(-48)" means " square root of -48 "
We'll factor and use the rule sqrt(x*y) = sqrt(x)*sqrt(y) to simplify this expression
sqrt(-48) = sqrt(-1*48)
sqrt(-48) = sqrt(-1)*sqrt(48) ... using rule mentioned above
sqrt(-48) = i*sqrt(48) ... use i = sqrt(-1)
sqrt(-48) = i*sqrt(16*3) ... factor
sqrt(-48) = i*sqrt(16)*sqrt(3) ... using rule mentioned above
sqrt(-48) = i*4*sqrt(3) ... Simplify
sqrt(-48) = 4i*sqrt(3) ... Rearrange terms
The final answer is 4i*sqrt(3), which is choice C