What concept explains the unified direction of the Sun's rotation and planetary orbits?

Conservation of angular momentum inherited from the parent cloud

A major strength of the nebular hypothesis is its ability to explain the systemic coherence in motion observed throughout the Solar System—specifically that the Sun rotates, and all major planets orbit, in the same counterclockwise direction when viewed from above the Sun's north pole. This organization is a direct consequence of the initial conditions of the system's progenitor. The entire system originated from a single, rotating cloud (the solar nebula). As this cloud underwent gravitational collapse, the principle of the conservation of angular momentum mandated that the rotation speed increased, but the overall direction of rotation was preserved. Since the planets formed from the material within this already spinning disk, their orbital motions are essentially inherited characteristics of that original spin.