An example of a component in engineering could be:

A mechanical part within a machine is indeed a fundamental example of a component in engineering. Components are basic elements that make up larger systems or assemblies and are essential in the design and functioning of mechanical systems. A mechanical part, such as a gear, a bearing, or a sensor, serves a specific function and contributes to the overall operation of the machine.

In contrast, a user interface, while important in engineering, specifically relates to how users interact with software or devices, rather than being a physical component. A sole engineer refers to a person rather than a physical or conceptual component of a system. A marketing strategy, although crucial for the success of engineering products, does not qualify as a component in the engineering sense since it pertains more to business practices than to systems design. Therefore, a mechanical part within a machine clearly represents a tangible and functional component of engineering.