Which of the following best describes a motorcycle?

A motorcycle is defined as a motor vehicle that is typically built with a rider's saddle, which is the seat designed for the operator. This definition encompasses the basic characteristics of motorcycles, highlighting their function as a motorized vehicle meant for transportation of individuals.

The other options do not accurately capture the essence of what a motorcycle is. A motorcycle is not a non-motorized vehicle for recreation, as it relies on an engine for operation. It also does not primarily serve the purpose of carrying goods; that description fits more closely to other vehicle types, such as trucks. Additionally, while tractors can have a saddle for a rider, they are fundamentally different in design and function, primarily focused on agricultural work rather than personal transportation. Thus, the definition provided best encapsulates the motorcycle's identity as a motor vehicle with a rider's saddle.