Tom Anderson observed that the unit cost for a particular cost $($cost # $101)$ decreased in February compared to January of this year. He further observed that the total cost for cost #$101$ was higher in February compared to January. All other things being equal, which of the following is most likely true?

A$.$

Cost # $101$ is a mixed cost and the volume of activity has decreased in February compared to January

B$.$

Cost # $101$ is a fixed cost and the volume of activity has increased in February compared to January

C$.$

Cost # $101$ is a mixed cost and the volume of activity has increased in February compared to January

D$.$

Cost # $101$ is a fixed cost and the volume of activity in February is the same as in January

E$.$

Cost # $101$ is a variable cost and the volume of activity has increased in February compared to January