Question

Astronomers think planets formed from interstellar dust and gases that clumped together in a process called _____.
1.stellar evolution
2.nebular aggregation
3.planetary accretion
4.nuclear fusion

Answer 1

If you have a good dictionary and look these words up, you'll find the answer.

Sra

Answer 2

Now you can reason this one out.
We are talking about planets

Not stars (stellar)
Not nebula
not fusion
so ----