If Acids Are Compounds That Release Protons (H⁺),how Is It

If acids are compounds that release protons (H⁺) ,how is it that SO_x and NO_x cause acid rain?

A) They react with hydrogen gas in the atmosphere to produce acids.
B) There is not sufficient evidence to indicate that these compounds actually do cause acid rain.
C) They react with water to form acids.
D) They react with ammonia to form acids.