Choose the One Alternative That Best Completes the Statement or Answers

Choose the one alternative that best completes the statement or answers the question.
Solve the equation
- $\sqrt{8 q-7}=7$

A) $\left\{\frac{21}{4}\right\}$

B) $\{49\}$

C) $\left\{\frac{49}{8}\right\}$

D) $\{7\}$