14 Eco-friendly travel is now one of the fastest-growing _________ in the industry, and many people embrace this promising development.
(A)problems
(B)trends
(C)conflicts
(D)setbacks

環保旅遊如今已成為旅遊業中成長最快的_________之一，許多人都樂於接受這一充滿希望的發展趨勢。