Which expression is equivalent to √-80

a. - 4 √5

b. - 4 √5i

c. 4 √5i

d. 4 √5

To simplify √-80, we can take out "i" from the root by using the relation i = √-1. Further factoring out 80, we can simplify it, which will be shown as follows:

√-80 = √ (-1) (16) (5) = 4i √5

Among the choices, the correct answer is C.