In the Figure, an Airport Luggage-Carrying Train with a Tractor $T$

Multiple Choice

In the figure, an airport luggage-carrying train with a tractor $T$ is pulling three luggage carts, $M_{1}, M_{2}$ , and $M_{3}$ with an acceleration of $1.2 \mathrm{~m} / \mathrm{s}^{2}$ . If $\mathrm{T}=300 \mathrm{~kg}, \mathrm{M}_{1}=200 \mathrm{~kg}, \mathrm{M}_{2}=100 \mathrm{~kg}$ , and $\mathrm{M}_{3}=100 \mathrm{~kg}$ , and air resistance is negligible, then the tension in the connection between cart $\mathrm{M}_{2}$ and cart $\mathrm{M}_{1}$ is

A) $480 \mathrm{~N}$ .
B) $840 \mathrm{~N}$ .
C) $240 \mathrm{~N}$ .
D) $0 \mathrm{~N}$ .
E) $120 \mathrm{~N}$ .