can you help me with these questions, please, thanks

Costs that change in the short run when quantity produced changes are called: fixed costs sunk costs variable costs O explicit costsJames works full-time but is considering not working so he can go to college full-time. James currently makes $35,000 per year. Going to college would cost $20,000 for a year of tuition. What is Jame's total economic cost of going to college for one year? $15,000 $20,000 O $35,000 O $55,000