b
(b)
When taken through $A B C[\triangle U+$ work $=$ heat absorbed $]$
Heat absorbed $=$ area under graph $+\Delta U=8$
$\Delta U=8-\frac{10 \times 200}{1000}=6$
when taken directly to $C$
$W+\Delta U=Q$
${\left[\frac{10 \times 200}{1000}+\frac{1}{2} \times \frac{2000}{1000}\right]+6=Q \Rightarrow Q=9 \,J }$