The best option is the first one (Six yards of rope costs $5.50). It is the lowest unit cost.
<u>Step-by-step explanation:</u>
For the given question case, first we should compare the unit costs of the choices provided and evaluate the best option.
Choice 1:
Six yards of rope costs $ 5.50
Choice 2:
Four yards costs $ 4.75
Thus, the best choice is the first one. Because it is the lowest unit cost.