Identify Angle ABC: Is This a 90-Degree Right Angle?

To solve this problem, we'll follow these steps:

• Step 1: Identify the angle measure provided.
• Step 2: Match the angle measure to the corresponding type of angle.
• Step 3: Choose the correct type of angle from the multiple-choice options.

Let's break down the process:

Step 1: The problem specifies that $\angle \text{ABC} = 90^\circ$.

Step 2: Recall the definitions of angle types. A right angle is defined as an angle that measures exactly 90 degrees.

Step 3: Out of the provided choices, select the one that represents a right angle.
- Right angle: $\angle = 90^\circ$ (Correct Choice)
- Acute angle: $\angle < 90^\circ$
- Obtuse angle: $\angle > 90^\circ$ and $\angle < 180^\circ$
- Flat angle: $\angle = 180^\circ$

Thus, the conclusion is that $\angle \text{ABC}$ is a Right angle.