Question

A student explains the Nebular theory of formation of planets as follows.

"A cloud of gas and dust in space, called nebula, began to rotate and condensed into a flattened disk. Gravitational force pulled the gas and dust closer together. This resulted in the nuclear fusion of gases and dust to create the sun and planets at the outer flattened portion of the disk."

What is the flaw in the student's explanation?

nuclear fission created the sun and planets

the nebula evaporated instead of condensing

the sun was formed at the center of the nebula

gravitational forces kept the gases well separated