"A" is not a graph it is a picture of the physical set up of the experiment. A step voltage stimulus is applied at the end of an 8 mm long axon and the current read at three different times, at 13, 35, and 100 ms, at 3 different places along the axon at 2.5, 5.0, nd 7.5 mm from the point where the stimulus is applied.
"B" shows four different graphs. The lowest shows the current at each point after 13 ms, the next shows the current at each point after 35 ms, and the third shows the current at each point after 100 ms. I presume the curve is interpolated from the values at 2.5, 5.0, and 7.5 mm where the current is measured. The fourth, dashed curve, is the projected curve "at t= infinity", extrapolated from the measured data.
"C" is the reverse of "B". While "B" has three graphs, each showing the current at different distances for a fixed time, "C" has three graphs, each showing the current at different times at a fixed distance.
