Step 1: Understanding the Clock Face.
The small hand on 5 and the big hand on 12 form a straight angle, as the angle between 12 and 5 is exactly 180°.
Step 2: Verifying the Options.
- Option (1): Obtuse angle is incorrect as the angle is 180°.
- Option (2): Acute angle is incorrect as the angle is greater than 90°.
- Option (3): A straight angle is 180°, which is the correct answer.
- Option (4): Reflex angle is incorrect, as the angle is not greater than 180°.
Conclusion:
Therefore, the correct answer is (3) Straight angle.