Which of the Following Works Best for Fusing Hydrogen

Which of the following works best for fusing hydrogen?

A) Bring the hydrogen nuclei together very slowly until they hold together.
B) Heat it up to such a high temperature that collisions cause the nuclei to fuse.
C) Hit the hydrogen nucleus with a neutron.
D) Hit the hydrogen nucleus with an electron.
E) Cool the hydrogen until the nuclei are at rest and then suddenly compress them.