Which effort to be more "green" has been undertaken by a number of college students? 

A)  They established agricultural research stations. 
B)  They established a Green Cup competition among dorms to see who eats the most vegetables. 
C)  They promoted the use of locally grown beef only. 
D)  They worked with faculty and administration to make environmental improvements on campus.

Option D states that the college students worked with the faculty and administration to make environmental improvements on campus, which is the most comprehensive and impactful effort to be more "green" among the given choices. Establishing agricultural research stations (option A) and establishing a Green Cup competition to see who eats the most vegetables (option B) promote eco-friendly practices, but they have limited scope and impact. Option C promotes the use of locally grown beef, which is sustainable and environmentally friendly, but it focuses on only one aspect of environmentalism.