Which is the most suitable answer here?
A second category of refrigerants currently available is the hydrochlorofluorocarbons (HCFCs). ¬†Although they contain chlorine, which is damaging to the ozone layer, they also contain_________, which makes them chemically less stable once they enter the atmosphere.¬† ¬†
A. Hydrogen B. Water C. Bromine D. Helium E. Heptane