To name an angle, the vertex must always be the middle letter when using three letters, or the only letter if using a single letter.

To name an angle, the vertex must always be the middle letter when using three letters, or the only letter if using a single letter.

• The angle shown has its vertex at point C.
• The rays forming the angle are CA and CE.

Let's evaluate the options:

• $\angle C$: This is a correct way to name the angle, as C is the vertex and there is only one angle at C.
• $\angle ACE$: This is a correct way to name the angle. The vertex C is in the middle, and A and E are points on the rays.
• $\angle AEC$: This name implies that E is the vertex of the angle. However, the vertex of the angle in the diagram is C, not E. Therefore, this is not a correct way to name the given angle.
• $\angle ECA$: This is a correct way to name the angle. The vertex C is in the middle, and E and A are points on the rays.

The option that is NOT a correct way to name this angle is $\angle AEC$.

The final answer is $\text{<AEC}$