Suppose a block moves across a rough horizontal surface at constant speed under the action of a horizontal 3-N force. Which statement concerning this situation is not true?

a. There is more than the 3-N horizontal force acting on the block.
b. The net force on the block is 3-N
c. The frictional force on the block has a magnitude of 3-N.
d. The net force on the block is zero Newtons.
e. The block is not accelerated.