A student walks 200\,m east from his home to the library and then immediately walks back along the same path to his home, taking a total of 8\,min for the round trip. Which of the following statements is true for the entire journey?
a) Average speed is non-zero, average velocity is zero.
b) Average speed is zero, average velocity is non-zero eastward.
c) Average speed is non-zero, average velocity is non-zero eastward.
d) Average speed is 0.42ms−1, average velocity is zero.