Answer:
The correct option is D.
Step-by-step explanation:
An an angle is called an obtuse angle if the measure of angle is lies between 90° and 180°. The angle θ is an obtuse angle if

The given statement is "An obtuse angle is an angle whose measure is greater than 90°."
It is an false statement, because all angles whose measure is more than 90°, are not an obtuse angle.
For example the angle 200° is more than 90° but not less than 180°, therefore the angle 200° is not an obtuse angle. The angle 180° is not an obtuse angle.
Therefore option D is correct.