Which of the following angles in standard position is an acute angle?

• A. $120°$
• B. $30°$
• C. $150°$
• D. $90°$

Answer: (B)

Verified step by step guidance

1. Recall the definition of an acute angle: an angle that measures greater than 0° and less than 90°.
2. Examine each given angle to determine if it fits the acute angle criteria: 120°, 30°, 150°, and 90°.
3. Check 120°: since 120° is greater than 90°, it is not acute.
4. Check 30°: since 30° is between 0° and 90°, it is an acute angle.
5. Check 150° and 90°: 150° is greater than 90°, and 90° is a right angle, so neither is acute.