According to the nebular theory, which of the following is not a requirement when describing any model of the solar system formation? a) where the solid seeds for planet formation come from to include condensation to metals. b) the location and composition of an asteroid belt. c) jovian (outer) planets are dense, rocky, and small, while terrestrial (inner) planets are gaseous and large. d) all planetary orbits are prograde (revolve from west to east or in a counter-clockwise direction).