Assertion (A) :  If $L=\underset{x\to 4}{\lim }{\left(\frac{{\log }_5\left(\frac{5x}{4}\right)}{{\log }_5\left(\frac{20}{x}\right)}\right)}^{{\left({\log }_5\frac{x}{4}\right)}^{-1}},$ then [L]  (where [.] denotes greatest integer function) is equal to 7
Reason (R) : $\underset{x\to a}{\lim }\left(f\left(x\right)\right){}^{g\left(x\right)}$   is always equal to  ${\left(e\right)}^k$ where   $k=\underset{x\to a}{\lim }\left[\left(f\left(x\right)-1\right)\times g\left(x\right)\right]$
 

Both (A) and (R) are correct and (R) is the correct explanation of  (A)

Both (A) and (R) are correct and (R) is not the correct explanation of  (A)

(A) is correct but (R) is not correct

(A) is not correct but (R) is correct