Final answer:
A constant is a value that cannot be altered by the program during its execution, meaning it remains the same throughout the program. It is not a data type, nor is it a procedure within a block of code.
Step-by-step explanation:
Which of the following is true of a constant? A constant is a value that cannot be altered by the program during its execution, which means the correct answers are:
- A. It cannot be changed by the program as it runs.
- B. It is a data type (This is incorrect; a constant is a value, not a data type).
- C. It is a procedure in a block of code (This is also incorrect; a constant is not a procedure).
- D. It can be changed by the program as it runs (This is incorrect; once defined, a constant cannot change).
An example to illustrate this concept is the speed of light, which is a constant value used in scientific equations and does not change.