A Tractor $T$ Is Pulling Two Trailers $M_{1}$ And $M_{2}$ , with a Constant Acceleration

Multiple Choice

A tractor $T$ is pulling two trailers, $M_{1}$ and $M_{2}$ , with a constant acceleration. $T$ has a mass of $200 \mathrm{~kg}, M_{1}$ has a mass of $100 \mathrm{~kg}$ , and $M_{2}$ has a mass of $150 \mathrm{~kg}$ . If the forward acceleration is $0.60 \mathrm{~m} / \mathrm{s}^{2}$ , then the horizontal force on the tractor due to the ground is (ignore air resistance)

A) $90 \mathrm{~N}$ forward.
B) $150 \mathrm{~N}$ forward.
C) $270 \mathrm{~N}$ forward.
D) $150 \mathrm{~N}$ backward.
E) $270 \mathrm{~N}$ backward.