Question

1. name the missing force... a) frictional force b) buoyant force c) weight force d) thrust

Explanation:

The person is pushing the block (applied force $F_A$), there is normal force $F_N$ perpendicular to the surface, gravitational force $F_g$ acting down - ward. When an object is on a surface and a force is applied to move it horizontally, the opposing force to the applied force is the frictional force. It acts in the direction opposite to the relative motion or tendency of relative motion between the object and the surface.

Answer:

a) frictional force