Question

atmospheric ozone concentration (one day period)
question: at what hour was there the greatest increase in ozone ppm in the valley region?
during hour 17
during hour 8
during hour 3
during hour 7

Explanation:

Step1: Observe the slope of the valley - region line

Check the steepness of the line representing the valley - region in the graph for each time - interval.

Step2: Compare the slopes at different hours

The slope of the line is steeper between hour 3 and hour 4 compared to other given time - points.

Answer:

During hour 3