#### Answer

Regular Sandwich is the best buy at $\frac{0.86 Dollar}{inches}$.

#### Work Step by Step

To find the rates we need to find Dollar per ounce.
So. Writing all options as a ratio.
Small = $\frac{5.99 Dollar}{5 inches}$
Regular = $\frac{6.89 Dollar}{8 inches}$
Large = $\frac{10 Dollar}{11 inches}$
Now, we need to find the lowest terms.
Small = $\frac{5.99 Dollar}{5 inches} \approx \frac{1.20 Dollar}{inches} $
Regular = $\frac{6.89 Dollar}{8 inches} \approx \frac{0.86 Dollar}{inches}$
Large = $\frac{10 Dollar}{11 inches} \approx \frac{0.91 Dollar}{inches}$
Now comparing all the rates Regular Sandwich is the best buy at $\frac{0.86 Dollar}{inches}$.