Final answer:
The internal energy of a thermodynamic system is increased by 300 J either by the transfer of heat or by doing work.
Step-by-step explanation:
The change in internal energy of a thermodynamic system can be determined by the sum of the heat added and the work done on or by the system, according to the First Law of Thermodynamics. The internal energy of a thermodynamic system is increased by 300 J either by the transfer of heat or by doing work.
In this case, since the internal energy is being increased by 300, it means that 300 J of energy is being added to the system either through the transfer of heat or by doing work. The internal energy of a thermodynamic system is increased by 300 J either by the transfer of heat or by doing work. Therefore, the correct answer is c) Heat added.