In each of the diagrams below, one or more external forces act on the indicated system. Which of the forces listed below are the reaction to the external force mentioned? (Select all that apply.)
(a) the mower exerts a force
upward on the Earth due to gravitational attraction
downward on the ground due to contact
downward on the Earth due to gravitational attraction
upward and to the left on the handle
upward on the ground due to contact