Answer
The voltage changes more slowly as time goes on.
Work Step by Step
The tangent line pass through the points (10, 3) and (30, 4)
The rate of change of voltage at t = 20 seconds is
The rate of change of voltage = $\frac{4-3}{30-10}$ = $0.05$ $V/s$
The tangent lines to it grow shallower, indicating that the voltage changes more slowly as time goes on.
