Which of the following best describes an electric vehicle (EV)?
a. A vehicle powered entirely by electricity, using batteries to store energy and electric motors for propulsion.
b. A vehicle that uses a combination of gasoline and electricity, with an internal combustion engine as the primary power source.
c. A vehicle that relies on a diesel engine for power, with an electric motor used solely for auxiliary functions.
d. A vehicle that runs on compressed natural gas (CNG) and includes a small electric motor for improved fuel efficiency.