The Basic Idea Behind the Planetesimal Hypothesis Is That

The basic idea behind the planetesimal hypothesis is that

A) planets form as a direct result of the nuclear fusion of nebular gases and planetesimals.
B) planets form from the remains of super-giant planetesimals that undergo nuclear fission and blow apart, thereby creating smaller objects-the planets.
C) early in the solar system's history, a star passed near to the Sun and pulled off gases that eventually condensed to form planets.
D) small grains of cosmic dust and other solids gradual accrete to form planetesimals that may grow to become protoplanets and eventually planets.