Final answer:
Statement 3, which posits an even distribution of gas throughout the solar system, is the least likely to be associated with the disk instability theory because the actual distribution of gas in the protoplanetary disk was not even.
Step-by-step explanation:
The question pertains to the concept of planet formation and, more specifically, the disk instability theory. Within this framework, we need to identify which statement is least likely to be associated with the theory. We evaluate each of the given options:
- Icy giants grew faster than terrestrial planets.
- Icy giants could grow quickly due to the location of their orbit.
- Outer planets' formation is due to an even distribution of gas throughout the solar system.
- Outer planets' formation began with a gassy core.
Statements 1, 2, and 4 are consistent with the disk instability theory, which suggests that icy giants and gas giants in the outer solar system formed quickly from an abundance of ices and gas, often starting with a solid core that rapidly accumulates gas. Statement 3, on the other hand, is the least likely to be associated with the disk instability theory because the distribution of gas in the protoplanetary disk was not even, being denser within a few astronomical units from the star, and less dense farther away, affecting how planets formed at different distances from the star.