Answer:
Neither. They will have equal change in the magnitude of momentum.
Step-by-step explanation:
Change in in momentum of a body is calculated as follows:
ΔP = FΔt
where ΔP is the change in momentum
and F is the force exerted on the object
and Δt is the change in time during the impact
The time it takes for the impact is the same for both objects. Also, according to Newton's third law, when object A exerts a force on on object B, B exerts an equal(magnitude wise) but opposite force on A. Therefore the value of F is also equal. This tells us that the magnitude of impulse will be the same for both the fly and the truck