The Results of a Dose-Response Assessment Often Are Plotted on a Graph

The results of a dose-response assessment often are plotted on a graph with the exposure level dose) on the x axis and the percent of the population experiencing an effect on the y axis. This graph usually looks like an S-shaped curve. At what point along the curve would you find the No Observed Adverse Effect Level NOAEL) ?

A) At the far left of the graph, at the beginning of the S-shape.
B) In the middle of the graph, where the S-shape is nearly vertical.
C) At the far right of the graph, at the peak of the S-shape.
D) The NOAEL would not appear on the graph.