Which tool is useful for holding a socket for angle turning?

The universal joint is the correct answer as it is specifically designed to allow flexibility and rotation in multiple directions when connecting a socket to a ratchet or handle. This adaptability is particularly beneficial for tasks that require angle turning or working in tight spaces where direct alignment between the tool and the socket is not feasible. The universal joint can pivot, which allows the socket to change angles and access fasteners that are not directly in line with the handle or driver.

In contrast, the other options serve different functions. A universal grip is designed for holding and manipulating tools but does not specifically aid in angle turning with sockets. A socket adapter changes the size of the socket fitting but does not facilitate angular movement. A wrench extension provides additional reach but lacks the flexibility needed for effective angle adjustments.