Answer:
all unit costs are $24.50 per cubic yard
Step-by-step explanation:
A "unit" is one of something. A "unit cost" is the cost of one of something. Sometimes, you are told what a unit is; sometimes you have to figure out a reasonable unit.
Here, we have cost in dollars and material volume in units of cubic yards. It is reasonable to assume the unit of interest is 1 cubic yard.
It should not be a mystery that the cost of 1 cubic yard will be 1/8 the cost of 8 cubic yards. That is, you find the unit cost by dividing the cost by the number of units:
A. ($196)/(8 yd³) = $24.50/yd³
B. ($490)/(20 yd³) = $24.50/yd³
C. ($637)/(26 yd³) = $24.50/yd³
