Explain an example of e-commerce?

Which of the following is an example of e-commerce?

a. a restaurant publishes its menus on its Web site so customers can decide what they want before coming to the restaurant.

b. A Web site generates maps and directions on how to get from one address to any other address in the U.S.

c. on a city's Web site, residents can access their tax bills and use their credit card to pay them over the Internet.

d. All of the above are examples of e-commerce.

e. none of the above is an example of e-commerce.