Answer:(1) Pre-solar nebula
(2). Planet formation
Explanation:
Nebular hypothesis says that the Solar System formed from the gravitational collapse of a fragment of a giant molecular cloud.
One of the collapsing fragments called the pre-solar nebula formed what became the Solar System.
The planet can also be formed by accretion. Accretion is a process in which planets began as dust grains in orbit around the central protostar.
When the terrestrial planets were forming, they remained immersed in a disk of gas and dust.
