What's the "greenest" industry?

Health care is a great field to go into. it is secure and in demand also salary is very decent considering the amount of schooling you get. eg. RN you only need an ociates or a bachelors degree, depending on where you you are looking at 46-60 grand per year+ benefits. Phycians-istant is masters degree and you are looking at 100grand/ year+benefits. this is not a bad field to go into.