Objective: How to cut drywall panels?

Which of the following solutions is more sound in terms of naive physics reasoning?

Select from the following. a). Cut through the paper into the gypsum core with a utility knife then while supporting the drywall sheet on the back apply pressure to the face causing it to break along the joint. Then cut through the paper on the back of the drywall sheet with your utility knife.; b). Cut through the paper into the gypsum core with a utility knife then without supporting the drywall sheet on the back apply pressure to the edges causing it to break along the joint. Then cut through the paper on the back of the drywall sheet with your utility knife.;
a).