A 50 m^3 vessel contains a mixture of 80% water and 10 m^3 of water vapor. If the internal pressure of the vessel reads 100 kPa, what is the internal energy of the system?
A) 4,060,000 kJ
B) 4,000,000 kJ
C) 60,000 kJ
D) 3,940,000 kJ