Which of the Following Illustrates the Marketing Concept in Action

Which of the following illustrates the marketing concept in action?

A) Three pediatricians set up a group practice,so that at least one is always available for emergencies.
B) Bank ATMs that dispense cash are placed in fast-food restaurants.
C) The Nevada auto registration office mails license tags to people,to reduce inconvenient waiting in line.
D) A veterinarian has office hours in the evening to see pets whose owners must work during the day.
E) All these answers are correct.