Which one supports the solar nebula theory of the origin of the solar system?

Question

a.Disks are rare around young stars.
b.Disks are common around young stars.
c.The sun is the least massive object in the solar system.
d.Planets are round.

Answer 1

b is not even true. Planet shape (d) has nothing to do with the origin of the solar system. That leaves a and b. Which makes more sense to you? Planets have to form out of something orbiting the star at different distances