If \([x]\) is the greatest integer less than or equal to \(x,\) and \([\sqrt{x}] = 5\) and \([\sqrt{y}] = 6,\) where

[Vincen]

If \([x]\) is the greatest integer less than or equal to \(x,\) and \([\sqrt{x}] = 5\) and \([\sqrt{y}] = 6,\) where \(x\) and \(y\) are positive integers, what is the greatest possible value of \(x + y ?\)

A. 61
B. 81
C. 82
D. 83
E. 85

Answer: D

Source: GMAT Club Tests