We are given that dy/dx = √(1 - y²). Find an expression for d²y/dx² in terms of x and y.

(a) d²y/dx² = y/√(1 - y²)
(b) d²y/dx² = 1 - y²
(c) d²y/dx² = -y/√(1 - y²)
(d) d²y/dx² = -1 + y²