The correct answer is option C, Planetesimal assembly
Accretion is the assembling of particle to form a massive object by virtue of gravitational attraction. Most of the celestial objects are formed by the accretion process. Planetesimals is an important step in the formation process of planet which involves the accumulation of dust and ice particles. Thus Planetary assembly work on the same principal of planetary accretion model and hence it can be stated as another name of planetary accretion model