Consider the following statements:
1. All machines consume energy.
2. Electricity provides energy.
3. Electrically operated machines are cheap to maintain.
4. Electrically operated machines do not cause pollution.
Which one of the following inferences can be drawn from the above statements?
(a) All machines are run by electric energy.
(b) There is no form of energy other than electricity.
(c) Most machines are operated on electric energy.
(d) Electrically operated machines are preferable to use.
