Which type of plumbing fitting would you most likely use to create a T-joint?

To create a T-joint in plumbing, the most suitable fitting is a tee. A tee fitting is specifically designed to allow the flow of water or other fluids to be redirected into two different directions from a single entry point, resembling the letter "T." This is essential in plumbing systems where branching of pipes is necessary to supply water or drainage to multiple fixtures from a single source.

Elbows, while crucial in altering the direction of pipe runs, are not designed for creating branching points. Nipples are short lengths of pipe used to connect two fittings, and reducers are utilized to transition between different pipe sizes. Therefore, while each of these fittings serves an important function in plumbing, the tee is the only one that fulfills the requirement for forming a T-joint effectively.