Which answer best explains how most scientists think that planets form? A. Large chunks of matter break off a star that collides with another star; these chunks then become planets orbiting the star. B. Large chunks of matter break off a planet that collides with a smaller body; these chunks gradually clump together to become a new planet. C. A rotating cloud of space dust and gases begins to flatten and condense, forming a new star; the remaining matter forms an accretionary disc around the star, gradually coalescing to form planets. D. A rotating cloud of space dust and gases begins to condense, forming a protoplanet; if the protoplanet is massive enough, its gravity will attract nearby matter until the protoplanet becomes large and round enough to be considered a planet.