fill in the blanks with passive form of verbs given in the brackets.

Numerous theories (a)_____ (profound) regarding the formation of the earth. It is said that the Earth (b)_____ (form) with the rest of the solar system which (c)_____ (consolidate) our interstellar dust. Earth's crust (d)_____(form) with different layers.

Don't give irrevelant answers otherwise I will report it.​