Which statement is true about nuclear fusion?

It is caused by the same process that causes nuclear fission.

It does not occur naturally in the solar system.

It has very low activation energy.

It produces nearly all the elements that are heavier than helium.

The correct statement about nuclear fusion is the last one: "it produces nearly all the elements that are heavier than helium". Nuclear fusion is the process of combination of two smaller atoms into a larger one. It requires a high activation energy, which is reached in the stars. Elements from He to Iron were formed in the Sun, but larger elements require a higher energy and are formed inside supernovas.