Bill Went to Millennium Park to Protest the Recent Budget

Bill went to Millennium Park to protest the recent budget cuts to education in Cook County. It was a spur of the moment thing and as a result he was alone in his efforts. Nonetheless he yelled and marched and held various signs up to get his point across. He is arrested and charged with rioting. Is this charge appropriate in the given circumstance?

A) No, he has committed aggravated disorderly conduct.
B) No, he has the right to freedom of expression.
C) Yes, he was disturbing the peace in a public place.
D) No, a riot requires more than just one person.