The closest to measure of the marked angle will be 90 degrees. (Option B).
How to calculate the measure of the indicated angle?
The closest to the measure of the marked angle in the shape is determined by comparing the shape of the marked angle with the angles provided in the options.
a 20 degrees angle will mostly have this shape "∠ " (far less than 90 degrees)
a 90 degrees angle will have this shape " ⊥ "
180 degrees angle will have this shape " ------"
So from the shape of the marked angle we can see that it is a little bit above 90 degrees, so the closest to measure of the marked angle will be 90 degrees.