# Water lilies on Day 0 = x
# Water lilies on Day 0+2 = 2*x
on Day 0, # water lilies = 1
Day 2 - 2
Day 4 - 4
Day 6 will be 8 and so on
Let suppose for simplicity the pond is full with 8 lilies only in 6 days (instead of 60 days in Question)
so if we start with 1 lily, the pond has 8 lilies on DAY 6 (6 days)
Suppose we started with 2 lilies on Day 0
Day 2 we would have 4 lilies and
Day 4 we would have 8 lilies the pond has 8 liles on DAY 4.
Therefore the pond is NOW full in only 4 days if we start with 2 (instaed of 1) . i.e. TWO lESS DAys. WHY? Because it takes exactly 2 days to double from 1 to 2 lilies.
the same logic would also apply for the given question. it would take 2 less days if we start with 2 lilies than if we start with 1 lily. since origianlly it takes 60 days to fill the pond if we start with 1 lily on Day 0, The number of days will reduce by 2 if we had instead started with 2 liles.
Hence Answer D
And likewise just suppose we were to start with 4 lilies instead of 1, guess how many days will it take to fill the pond?
[spoiler]60 - 4 = 56 (since it takes 4 days to grow from 1 lily to 4)[/spoiler]