Following an apparent terrorist attack, numerous patients present with shortness of breath and persistent coughing. A green haze is noted in the area in which the patients are located. Which of the following agents should you suspect they were exposed to?

A: Chlorine (CL)
B: Phosgene oxime
C: V agent (VX)
D: Tabun (GA)

Answer: A: Chlorine (CL)