[单选题]
A $100-cm^{3}$ container has 4 g of ideal gas in it at 250 kPa. If the volume is changed to $50 \; cm^{3}$ and the temperature remains constant, what is its new density?
A. $400 \; kg/m^{3}$
B. $250 \; kg/m^{3}$
C. $80 \; kg/m^{3}$
D. $50 \; kg/m^{3}$
