Which is the best definition of a prokaryotic cell?

it has a cell wall but lacks a well–defined nucleus and organelles, and its cytoplasm doesn't have much structure.
it contains a membrane–bound nucleus and organelles, and its organelles have specialized duties.
it contains a membrane–bound nucleus, a large central vacuole, a cell wall, a cell membrane, and chloroplasts.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.

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.