Final answer:
In the context of flowcharts for programming, a rectangle shape is used to represent a process step like calculating the area of a shape. A diamond is for decision-making, a rounded rectangle for start or end points, and a parallelogram for input or output steps. Therefore correct option is C
Step-by-step explanation:
The question concerns the creation of a flowchart for a program designed to calculate the area of a chosen polygon, either a triangle or a rectangle. In the context of flowcharts, different shapes represent different types of actions or steps in a process. A rectangle is commonly used to represent a process step, like calculating the area of a shape, whereas a diamond is used for decision-making. The rounded rectangle is typically used for the start and end points of the flowchart, and the parallelogram is used for input or output, such as obtaining user choices or displaying results. Therefore, the correct shape to use when you are calculating the area of a polygon in a flowchart is the rectangle.