Step-by-step explanation:
The purchaser of "closed-source" software does not have access to the "source code" so they cannot modify the program.
In closed-source software, the source code is not publicly available and is only accessible by the software vendor or authorized parties. The end-user of the software is provided with a compiled executable program that can be installed and run on their system, but they cannot access or modify the underlying source code. Closed-source software is often used for commercial products and proprietary software that are protected by intellectual property laws. In contrast, "open-source" software is publicly available and its source code can be accessed and modified by anyone, subject to certain license agreements.