Clennon Production Company planned to use $1$ yard of plastic per unit budgeted at $$81$ a yard. However, the plastic actually cost $$80$ per yard. The company actually made $3,900$ units, although it had planned to make only $3,300$ units. Total yards used for production were $3,960.$ How much is the total materials variance?

$$3,960F$

$$900U$

$$4,860U$

$$48,600U$