In the expansion of
\left(1 \plus{} x \plus{} x^2 \plus{} \cdots \plus{} x^{27}\right)\left(1 \plus{} x \plus{} x^2 \plus{} \cdots \plus{} x^{14}\right)^2,
what is the coefficient of x28?
<spanclass=′latex−bold′>(A)</span>195<spanclass=′latex−bold′>(B)</span>196<spanclass=′latex−bold′>(C)</span>224<spanclass=′latex−bold′>(D)</span>378<spanclass=′latex−bold′>(E)</span>405