Question

in order to recreate the process of energy production that takes place in the sun, scientists use hydrogen gas and add heat and pressure. hydrogen gas, add heat, and remove pressure. helium gas and remove heat and pressure. helium gas, remove heat, and add pressure.

Explanation:

The Sun's energy - production process is nuclear fusion where hydrogen fuses into helium. This requires high - heat and high - pressure conditions.

Answer:

hydrogen gas and add heat and pressure.