The correct answer is: 180°
Explanation:
Let's consider each angle one by one:
45°: If we rotate the above figure by 45°, it will not map onto itself; rather it will make 45° angle with the correct figure.
90°: If we rotate the above figure by 90°, it will be perpendicular to the given figure.
180°: If we rotate the above figure by 180°, it will map onto itself exactly.
360°: If we rotate the above figure by 360°, it will map onto itself exactly.
However, as the question is about the least angle, hence, in this case, the correct answer is 180° (since 180° < 360°).