Gerald performed an experiment to determine if photosynthesis was affected by the color of light that a plant received. The data from his experiment are shown in the table below.
 Color of Light
 Number of plants
 Average volume of oxygen produced (mL)
 green
 4
 0.50
 orange
 4
 2.0
 blue
 4
 5.0
 Which format should he use to present his data?
 bar graph
 chart
 line graph
 pie graph