Which of the following best describes an electric bicycle?

The definition of an electric bicycle encompasses its ability to be powered by both an electric motor and human effort, which sets it apart from traditional bicycles. An electric bicycle is specifically designed to facilitate movement using either the electric motor alone or in conjunction with the rider's own pedaling. This dual capability allows for more versatility and ease of use, particularly in varying terrain or for riders who may need assistance when pedaling.

The other options do not accurately capture this function. A bicycle solely propelled by human power is a conventional bicycle and does not include the electric motor feature. The description of a bicycle that can only be used on stationary tracks refers to a stationary bike or exercise bike, which lacks the mobility characteristic of electric bicycles. Lastly, a motorcycle with pedals does not fit the definition of an electric bicycle as it typically refers to a different class of vehicle altogether, which primarily operates as a motorcycle with added pedals rather than integrating the characteristics of both bicycles and electric propulsion.