Answer:
Option D
Explanation:
$A$ can do 1 work in 10 days
$B$ can do 1 work in $\frac{(9\times 5)}{3}$ = 15 days
$C$ can do 1 work in $\frac{(8\times 3)}{2}$ = 12 days
$A+B+C$ 's 1 day work $=\frac{1}{10}+\frac{1}{15}+\frac{1}{12}$ $=\frac{1}{4}$
They can complete the work in 4 days