Health Valley is a brand of food, such as breakfast cereals, that uses all natural and organic ingredients. Moreover, it only purchases grain from organic farms. It states on its packages that "organic farming helps keep our food pure and protects our land and water from harmful substances. By supporting dozens of small organic farms, Health Valley helps protect a way of life for these family farmers, and helps ensure a safer and healthier Earth for you and your children." This is an example of _____.

A.green marketing
B. clean marketing
C. environmental marketing
D. activist marketing
E. cause-related marketing