Final answer:
A quadratic equation has two solutions.
Step-by-step explanation:
A quadratic equation, which is option A, has two solutions. A quadratic equation is an equation of the form ax^2 + bx + c = 0, where a, b, and c are constants and a ≠ 0. The solutions to the quadratic equation can be found using the quadratic formula: x = (-b ± √(b^2 - 4ac))/(2a). This formula gives both the positive and negative solutions, resulting in two solutions.