Sheffield Corp. planned to use $1$ yard of material per unit budgeted at $$81$ a yard. However, the material actually cost $$80$ per yard. The company actually made $3900$ units, although it had planned to make only $3300$ units. Total yards used for production were $3978.$ What is the total materials variance?

$$3978F$

$$6318U$

$$2340U$

$$48600U$