On the x-axis and at a distance x from the origin, the gravitational field due to a mass distribution is given by Ax/(x² + a²)³/² in the x-direction. The magnitude of gravitational potential on the x-axis at a distance x, taking its value to be zero at infinity, is
(1) A(x² + a²)³/²
(2) A/(x² + a²)³/²
(3) A/(x² + a²)¹/²
(4) A(x² + a²)¹/²
