The correct answer is: D. Lifts and hoists.
A reluctance motor is a type of electric motor that uses the principle of magnetic reluctance to produce torque. It is a simple, rugged, and reliable motor that is well-suited for applications where high starting torque and low maintenance are required.
Reluctance motors are often used in lifts and hoists because they can provide the high starting torque required to lift heavy loads. They are also relatively inexpensive and easy to maintain, which makes them a good choice for applications where cost and reliability are important.
Electric shavers, refrigerators, and signalling and timing devices typically do not require the high starting torque that reluctance motors can provide. In addition, these devices are often used in applications where cost and size are important, and reluctance motors can be more expensive and larger than other types of motors.
Therefore, the best application for a reluctance motor is in lifts and hoists, where high starting torque and low maintenance are required.