which is the third step in the fusion process?

Brief Explanations:

In the proton - proton fusion process in stars, two protons combine to form a deuteron (first step). Then a deuteron and a proton combine to form helium - 3 (second step). Finally, two helium - 3 nuclei combine to form helium - 4 and release two protons. The third image shows the combination of two helium - 3 nuclei to form helium - 4, which is the third step in the fusion process.

Answer:

The third image (where two helium - 3 nuclei combine to form helium - 4 along with release of protons)