https://gateoverflow.in/30720/tifr2016-b-7
the above question is already discussed
but still am not clear enuf
can someone help
As a hint: for analysis of asymptotic complexity, take Log ( n! ) = n Log n.
Proof: https://stackoverflow.com/questions/2095395/is-logn-%CE%98n-logn use this and you will easily get answer for every option. In case you still have any query, please ask specifically what you are not able to understand.