A tectonic plate applies a downward force onto the asthenosphere, which lies beneath the plate. According to Newton's 3rd Law, which can be described as the law of action-reaction,
the asthenosphere applies a force of equal magnitude upward onto the tectonic plate.
the asthenosphere applies a force of double magnitude downward as well.
the asthenosphere applies a force of double magnitude upward onto the tectonic plate.
the asthenosphere applies a force of equal magnitude downward as well.