Need help please!

A student was asked to solve for √x = -1, is the student correct?

√x = -1
(√x)² = (-1)²
x = 1

(a) Yes, because x = 1 is the only real solution.
(b) Yes, because x has infinitely many solutions.
(c) No, because x is a complex number.
(d) No, because there is no solution for x.

Write a conclusion based on your answer.