This is a question with answer options. Goal: use steel wool to clean the pipe

Which of the following methods is more reasonable for accomplishing this goal?

pick from the following.
(a). Wearing gloves to protect your hands, run the steel wool along the middle of the pipe, inside and out;
(b). Wearing gloves to protect your hands, run the steel wool along the ends of the pipe, inside and out;...I think the answer is
(b).