The question asks what Water, Electricity, and Rickshaw have in common, given that they have all been used by people. Let's evaluate the options:
a) Patent: A patent is a legal right granted for an invention, protecting the inventor's idea. While electricity and rickshaws may involve patented technologies, water as a natural resource cannot be patented (though specific water-related technologies can be). This option doesn't fit all three. Incorrect.
b) Skill: A skill is an ability acquired through practice, like cooking or driving. Water, electricity, and rickshaws are not skills; they are resources or objects used by people, though using them might require skill (e.g., driving a rickshaw). This option doesn't apply to all. Incorrect.
c) Utility: In economics and general usage, "utility" refers to the usefulness or benefit provided by a good or service to satisfy human needs. Water is useful for drinking and cleaning, electricity for powering devices, and a rickshaw for transportation. All three provide utility to people through their use, making this the best fit. Correct.
d) Potential: Potential refers to the capacity for something to develop or be useful in the future (e.g., potential energy). While water, electricity, and rickshaws have potential for use, the question emphasizes their actual use by people, not their potential. This option is less fitting than utility. Incorrect.
Conclusion: Water, Electricity, and Rickshaw are all examples of c) Utility, as they are resources or services used by people to fulfill needs, providing usefulness or benefit.