Which of the following is an equivalent fraction of $\frac{5}{7}$ with denominator 77?

We have $\frac{5}{7}$.

We observe that 7 × 11 = 77. 

Therefore, we multiply the numerator and denominator by 12 to obtain the equivalent fraction.

Now,

$\frac{5\times 11}{7\times 11}=\frac{55}{77}$

Hence, $\frac{55}{77}$ is an equivalent fraction of $\frac{5}{7}$ with denominator 77.