Question: The value of `log_2 (log_5 625)` is :
A
B
C
D
`2`
B
`5`
C
`10`
D
`15`
Note: Let `log_5 625 = x.`
Then,`5^x = 625`
`= 5^4 or x = 4.`
Let `log_2 (log_5 625) = y.`
Then,`log_2 (4) = y`
`or 2^y = 4 = 2^2.`
So,`y = 2.`
:.`log_2 (log_5 625) = 2.`