Can anyone me with answering this question? : an accelerating (speeding up) body has a net force acting in the direction of motion. true or false? why?

That's true.

Netwon's second law states that the resultant of the forces F acting on a body is equal to the product between its mass m and its acceleration a:

This means that if the net force acting on an object is different from zero (term on the left), than the acceleration of the object (term on the right) must be different from zero as well, and therefore the body is accelerating.

In particular, both F and a in the equation are vectors: this means that if the acceleration is positive, F and a have the same direction. In this problem, the acceleration is positive (because the object is speeding up), therefore the force and the acceleration have same direction.