InterviewBit Problems   CHOOSE2 : Unsolved

About the CHOOSE2 : Unsolved category (1)
Is the options are Wrong? (1)
Is logn in above question means log base 10 or 2? (4)
Are we expected to do this without a calculator? (3)
What's the best way to approach these type of problems? (13)
Solution- Better Explanation (1)
Increasing order of complexity (11)
I think this is correct (2)