What kind of angle is each internal angle of a square

For a square, the inner angles will all be Right Angles, meaning they have a measure of 90°. This is because all 2D shapes have an inner angle measure of (n-2)180° where n is the number of sides and all 4 angles of a square are equal.
This means that the measure of each angle in a square is:

Thus each inner angle has a measure of 90°.

It is going to be the third choice