A particle is moving along an axis so that its potential energy is decreasing from point A to B, at a critical point at point B, increasing from point B to D, at a critical point at point D, and decreasing after that. Identify all of the following three statements that are true regarding this particle: 1) Point A is a stable equilibrium; 2) Point B is an unstable equilibrium; 3) Point D is a stable equilibrium.