A football goalkeeper moves across her goal in a straight line. Her motion is shown on the following graph of horizontal position xxx vs. time ttt. Graph of x (in meters) vs. t (in seconds). The y-intercept is at (0,0), then x increases linearly from 0 m to 2 m over 4 s, stays constant at 2 m from 4 to 8 seconds, and then decreases linearly from 2m to 0 m between 8 s and 12 s. Graph of x (in meters) vs. t (in seconds). The y-intercept is at (0,0), then x increases linearly from 0 m to 2 m over 4 s, stays constant at 2 m from 4 to 8 seconds, and then decreases linearly from 2m to 0 m between 8 s and 12 s. What is the average speed of the goalkeeper between the times t=4\text{ s}t=4 st, equals, 4, start text, space, s, end text and t=12\text{ s}t=12 st, equals, 12, start text, space, s, end text? Choose 1 Choose 1 (Choice A) A -0.25\,\dfrac{\text m}{\text s}−0.25 s m minus, 0, point, 25, start fraction, start text, m, end text, divided by, start text, s, end text, end fraction (Choice B) B 0.50\,\dfrac{\text m}{\text s}0.50 s m 0, point, 50, start fraction, start text, m, end text, divided by, start text, s, end text, end fraction (Choice C) C -0.50\,\dfrac{\text m}{\text s}−0.50 s m minus, 0, point, 50, start fraction, start text, m, end text, divided by, start text, s, end text, end fraction (Choice D) D 0.25\,\dfrac{\text m}{\text s}0.25 s m