Prezi prepared the following contribution format income statement based on a sales volume of $2,000$ units $($the relevant range of production is $500$ units to $1,500$ units$)$ of Product Line #$2.$

Sales $$20,000$

Variable Expenses $12,000$

Contribution Margin $8,000$

Fixed Expenses $6,000$

Net Operating Income $ $2,000$

One member of Prezi$$s board $($Mr$.$ Adrian$)$ has challenged the fixed expenses. Mr$.$ Adrian says $$There is no such thing as fixed costs. All costs change over the long term.$$ Is this a true statement? How would you respond to this comment from a board member?