For choice (a);
[tex]\begin{gathered} 6\text{ ounces of chocolate for 2.49} \\ \text{Per ounce=}\frac{2.49}{6} \\ \text{Per ounce=\$0.415} \end{gathered}[/tex]For choice (b);
[tex]\begin{gathered} 8\text{ ounces of chocolate for 3.32} \\ \text{Per ounce=}\frac{3.32}{8} \\ \text{Per ounce=\$0.415} \end{gathered}[/tex]Both options (a) and (b) have the same price per ounce which is $0.415.
Therefore, none of them is a cheaper option.