Question

Where has the process of nuclear fusion been occurring for over four billion years

Answer 1

Inside the Sun.

Step-by-step explanation:

Inside the Sun, this process begins with protons (which is simply a lone hydrogen nucleus) and through a series of steps, these protons fuse together and are turned into helium. This fusion process occurs inside the core of the Sun, and the transformation results in a release of energy that keeps the sun hot.