To find the measure of the angle MKN in the square MNKL, we shall take a reminder of some of the properties of a square.
Some of these are;
(1) All four sides are equal
(2) All four angles are equal
(3) All four angles measure 90 degrees each
The two diagonals bisect each other at 90 degree angles, that is, the diagonals are perpendicular.
Let us now isolate the triangle MKN;
Note that the diagonal MK which is now one side of the triangle MKN, bisects the angle K into two (that is 90 degrees divided by 2).
The same applies to the angle at point M.
Therefore;
ANSWER:
The third option is the correct answer