4. When a star is on the main sequence, it is (1 point) O converting hydrogen into helium through nuclear fusion
O converting uranium into helium through nuclear fusion
O burning hydrogen and oxygen to make heavier elements
burning radiolactive elements to create lighter elements

Producing disposable grocery bags consumes resources. recycling disposable bags is a solution that can recover some of the resources used to make new bags. which of the following behaviors could further refine the solution? a. disposing of bags by burning them b. reusing bags whenever possible c. using bags at once so that they do not break d. using only nonrenewable materials to make new bags subject is environmental science for apex users