Final answer:
Threaded couplings, which are commonly used in engineering to connect two shafts, consist of male and female parts, where the male threads fit into the female threads to secure the connection.
Step-by-step explanation:
Couplings are devices used to connect two shafts together at their ends for the purpose of transmitting power. In engineering, there are various types of couplings that serve different functions and have different designs. The type of coupling that consists of male and female parts is referred to as a threaded coupling (Option B). Threaded couplings feature threads where one part has a protrusion or threads that are male, while the other part has corresponding inward threads that are female. When assembled, these parts are screwed together, thereby securing the connection and allowing for the transmission of torque.
The term 'sexless couplings' does not apply here as it is not commonly used in this context. Unthreaded or nonthreaded couplings refer to those that do not use a screw mechanism for connection. They might use methods such as clamping, welding, or the use of pins for connection, and thus do not have distinct male and female components that thread together.