[ 501 ] Physical Science GED ® TEST SCIENCE FLASH REVIEW • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • In a chemical reaction, the chemist follows the concentrations of four substances (A–D) over time. The data are shown in the graph. Concentration Time A C D B Which chemical reaction is the proper conclusion from the data? A. A + B → C + D B. B + D → A + C C. A + C → D D. C + D → A