An ideal gas expands in volume from $1\times 10^{-3}{\text{m}}^3$ to $1\times 10^{-2}{\text{m}}^3$ at $300\text{K}$ against a constant pressure of $1\times 10^5{\text{Nm}}^{-2}$. The work done is:

1. A
   $-900\text{J}$
2. B
   $900\text{kJ}$
3. C
   $2780\text{kJ}$
4. D
   $-900\text{kJ}$