Final answer:
An elbow fitting is used to make an angled turn in piping systems, commonly at angles like 45°, 60°, or 90°, and it is distinct from other types of fittings such as straight, tee, and cross fittings.
Step-by-step explanation:
The fitting that makes an angled turn in piping, such as at 45°, 60°, or 90°, is known as an elbow fitting. This type of fitting is commonly used to change the direction of a pipe in a plumbing system. Options like straight fittings, tee fittings, and cross fittings have different purposes. A straight fitting is used when the pipes are to be connected in a straight line, a tee fitting is used to split the flow in two different directions, and a cross fitting is used to connect four pipe sections together.