A bit confused in one question of Mathematics of AILET 2016

I was solving AILET 2016 (Mathematics) for posting solutions to this website. I came to this question (No. 143), “In a garden there are 8...

A little more in Mathematics (in AILET) gives you much more.

The AILET paper of 2015 in terms of level of Mathematics questions was a real tough, but its toughness was a boon for the AILET aspirants...