15 Scientists found harmful particles in dolphins’ breath off Florida, raising _________ for their health and the environment.
(A)delight
(B)satisfaction
(C)indifference
(D)concerns

科學家在佛羅裡達附近海域海豚的呼吸中發現了有害顆粒，這引發了人們對海豚健康和環境的____。