Correct Answer is B, Fixed.
An expense that is constant each month is called a Fixed Expense.
There are many expenses that we have to meet in our daily lives. We usually plan our expenses on monthly basis. There are some Fixed Expenses, some are Variable expenses, some are uncertain expenses.
Fixed expenses can be our Rent of house, our internet package bill, salaries to servants, etc. Variable expenses can be our electricity bills, telephone bills, water bills, groceries, etc. Uncertain expenses may include any sickness expense, or expense incurred on a function, etc.