What is going on in this situation?

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

Which best describes how fluids change as they travel through different portions of the convection currents? they change to solids at the outer portion of the convection currents. they change to solids at the inner portion of the convection currents. they become more dense at the outer portion of the convection currents. they become more dense at the inner portion of the convection currents

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?