Average maintenance costs are $$1\mathrm{.}50$ per machine hour at an activity level of $8,000$ machine hours and $$1\mathrm{.}20$ per machine hour at an activity level of $13,000$ machine hours. Assuming that this activity is within the relevant range, total expected maintenance cost for a budgeted activity level of $10,000$ machine hours would be closest to which of the following?

a$.$ $$13,440$

b$.$ $$11,433$

c$.$ $$16,128$

d$.$ $$15,000$