c
\(\begin{array}{l}
Chenge\,in\,momentum\, = Area\,under\,F - graph\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,in\,that\,{\rm{interval}}\\
\,\,\,\,\,\,\, = Area\,of\,\Delta ABC - Area\,of\,{\rm{rectangle}}\,CDEF\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + Area\,of\,{\rm{rectangle}}\,{\rm{FGHI}}\\
\,\,\,\,\,\,\, = \,\frac{1}{2} \times 2 \times 6 - 3 \times 2 + 4 \times 3 = 12\,N\,s
\end{array}\)
