Dave pushes his four-year-old son thomas across the snow on a sled. as dave pushes, thomas speeds up. which statement is true?

Unfortunately, you have not included in here the choices in which we could select our answer/s from. However, it may be noted that according to Newton's second law of motion,

F = m x a

where F is force, m is mass and a is acceleration. With the same mass, increasing the force by pushing harder, the object accelerates. Thus, increasing the speed of Thomas.