Final answer:
In a program control flow chart, a parallelogram represents an input/output statement, such as when a program requires user input or needs to display something to the user.
Step-by-step explanation:
In a program control flow chart, a parallelogram is used to represent a input/output statement. This type of symbol is utilized when the program needs to receive input from a user or display output to the user. For example, if you were programming a calculator, you would use a parallelogram to represent the step where the user is prompted to enter a number, or where the result of a calculation is shown to the user.
A parallelogram is used to represent a decision statement in a program control flow chart.
A decision statement is used when the program needs to make a choice between two or more options based on a condition.
For example, in a flow chart representing a program that calculates a student's grade based on their test score, a parallelogram would be used to represent the decision of whether the test score is above a certain threshold.