A can do a piece of work in $20$ days and B can do the same work in $30$ days. If they work together on it for $2$ days, then what fraction of the work will be left?

1. A
   $\frac{5}{7}$
2. B
   $\frac{3}{5}$
3. C
   $\frac{5}{6}$
4. D
   $\frac{5}{8}$