Answer:
c
Explanation:
x³ - y³ ← is a difference of cubes and factors as
x³ - y³ = (x - y)(x² + xy + y²)
Given
+
= - 1
Multiply through by xy to clear the fractions
x² + y² = - xy ← substitute into second factor of expansion
x³ - y³ = (x - y)(- xy + xy) = (x - y) × 0 = 0 → c