Answer
See below.
Work Step by Step
Let $x=2$ and $y=3$, then $T(x+y)=T(5)=a+b+c+1$.
But $T(x)=a+b+c+1$ and $T(y)=a+b+c+1$, thus $T(x)+T(y)=2(a+b+c+1)\ne a+b+c+1=T(x+y)$.
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