A plastic ball in a liquid is acted upon by its weight and by a buoyant force. The weight of the ball is 2.6 N. The buoyant force has a magnitude of 4.4 N and acts vertically upward. At a given instant, the ball has zero velocity. At that instant, an external force acting on the ball imparts an acceleration of 3.0 m/s2 in the downward direction of the ball. The external force, including direction, is closest to: