At x=0
[tex]\begin{gathered} f(x)=14 \\ c=14 \end{gathered}[/tex]at x=1
[tex]\begin{gathered} f(x)=10.5 \\ a+b=10.5-14 \\ a+b=-3.5 \end{gathered}[/tex]at x=2
[tex]\begin{gathered} f(x)=8 \\ 4a+2b=8-14 \\ 4a+2b=-6 \end{gathered}[/tex]a=1/2
So correct option is (c).