The Average Reaction Rate Over a Time Period in Graph

The average reaction rate over a time period in graph b can be found by

A) taking the average of the rate every 100 s.
B) drawing a line tangent to the curve at the initial and final times, and then averaging.
C) drawing a line tangent to the curve at that point.
D) subtracting the final concentration from the initial concentration and dividing by the time interval.
E) subtracting the final time from the initial time and dividing by the concentration interval.