Controlled Experiments Are Most Appropriate for Testing Which of These

Multiple Choice

Controlled experiments are most appropriate for testing which of these hypotheses?

A) A meteorite collision with Earth caused the extinction of the dinosaurs.
B) Diets high in saturated fats cause cardiovascular disease in humans.
C) Increased carbon dioxide levels in the atmosphere have caused global temperatures to rise.
D) Introduction of water-recycling systems conserves water and reduces factory-operating costs.