Final answer:
If the force acting on Tina's truck increases while its mass remains constant, the acceleration of the truck will increase.
Step-by-step explanation:
When the force exerted by Tina's truck increases with its mass remaining constant, the acceleration of the truck will increase according to Newton's second law, which states that acceleration (a) is directly proportional to net force (F) and inversely proportional to mass (m), represented by the formula a = F/m. As the force increases and the mass remains constant, the acceleration must increase to maintain the proportionality (a = F/m). So the correct answer is A) The acceleration increases.