a pair of equivalent expression can be seen in option A and B
Explanation:[tex]\begin{gathered} a)\text{ (}\sqrt[4]{81})^7=81^{\frac{7}{4}} \\ \text{Hnece, (}\sqrt[4]{81})^7\text{ and }81^{\frac{7}{4}}\text{ are equal} \end{gathered}[/tex][tex]\begin{gathered} b)6^{\frac{7}{2}}\text{ can be written as (}\sqrt[]{6})^7 \\ \sin ce\text{ }6^{\frac{7}{2}}\text{ and (}\sqrt[]{6})^7\text{ are the same, they are equal} \end{gathered}[/tex][tex]\begin{gathered} c)5^{\frac{2}{3}}is\text{ written as }\sqrt[3]{^{}\mleft(5\mright?^{}})^2 \\ 5^{\frac{2}{3}}\text{ is not the same as }(\sqrt[]{5^{}})^3 \end{gathered}[/tex][tex]\begin{gathered} d)7^{\frac{5}{7}}\text{ can be written as }\sqrt[7]{(7)^5} \\ \sqrt[7]{(7)^5}\text{ is not the same as (}\sqrt[]{7)^5} \\ \text{hence, }7^{\frac{5}{7}}\text{ is not the same as (}\sqrt[]{7)^5} \end{gathered}[/tex]The options that are equal are equivalent.
Hence, a pair of equivalent expression can be seen in option A and B