A) Stephen Hales is called the father of plant physiology for his extensive research on photosynthesis.B) Joseph Priestley showed that animals exhale carbon dioxide (impure air) and plants give out oxygen (pure air).C) Ingenhousz showed that light is essential for photosynthesis.D) Von Helmont proved that plants require minerals from the soil for photosynthesis.So the correct answer is 'Priestley'.