Let $\mathrm{f}\left(\mathrm{x}\right)=\left\{\begin{array}{cc}{\mathrm{x}}^2-4\mathrm{x}+3,& \mathrm{x}<3\\ \mathrm{x}-4,& \mathrm{x}\ge 3\end{array}\right.$and $\mathrm{g}\left(\mathrm{x}\right)=\left\{\begin{array}{cc}\mathrm{x}-3,& \mathrm{x}<4\\ {\mathrm{x}}^2+2\mathrm{x}+2,& \mathrm{x}\ge 4\end{array}\right.$
Then which of the following is/are true?

• A

  $(\mathrm{f}+\mathrm{g})(3.5)=0$

• B

  $\mathrm{f}\left(\mathrm{g}\right(3\left)\right)=3$

• C

  $\left(\mathrm{fg}\right)\left(2\right)=1$

• D

  $(\mathrm{f}-\mathrm{g})\left(4\right)=0$