Amajor obstacle to developing good human relations skills is that

a. human relations aren't rewarding.
b. common interests won't to keep a conversation going.
c. people fear taking risks.
d. few persons have common interests.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.