In a graph with several intervals o data how does a constant interval appear? What type of scenario produces a constant interval?

A horizontal line; a melting ice cube.

Step-by-step explanation:

A constant interval appears as a horizontal line. The graph in the interval has a slope m = 0.

Here's an example of a constant interval.

You take an ice cube from the freezer and place it in a container on the counter.

The temperature of the ice cube is - 5 °C. The ice cube will warm to 0 °C, and then it will start to melt. While it is melting, the temperature is constant at 0 °C.

When the ice has completely melted, the water will start warming to room temperature.

A plot of temperature vs. time would look something like the graph below.

The interval AB, where the ice is melting, is a constant interval.