Answer:
d.) discretionary expenses
Step-by-step explanation:
We can explain going further into what is each item.
A and B are your income (for this question don’t sweat about the difference between gross and realized). They will constitute all the money you have in that period (the period will depend on the regularity of your income, it could be weekly, monthly, etc.).
Your fixed expenses are the things you will expend money on which, no matter what happens, will not change (it could be your rent, tax, health insurance, etc.).
Discretionary expenses, however, are costs that are things that you WANT, not NEED. It could go anywhere from a new shoe to a new boat (if you´re feeling rich, that is lol). That kind of expense will impact your available money (hey, nothing is free) but is not part of your budget as it is not a planned cost.
However, is important to note that if you wanna be super Monica Geller with your money you should forecast your discretionary expenses. Using your history as a base for calculating will eliminate most of the margin error.