How is/was Uranium formed?

Question

I asked this to my teacher today but he didn't know, and I've tried searching the Web but all these different answers came up.

So, "How Is Uranium Formed?"

Answer 1

Basically, it is formed in and expelled from stars when they explode.

Answer 2

I think it formed when the aliens spued out of the volcanoes during the beginning of the earth and time and the universe.

Answer 3

Uranium is heavier than iron.

It takes energy to fuse that many nuclear partivles together.

The conditions neccessary are found only in a

massive exploding star.