To answer this question, you need to understand the structure of an Easytrieve program.
Option A) Activity - This option is correct because the Activity section is the only mandatory section of an Easytrieve program. The Activity section contains the main logic and processing instructions of the program.
Option B) Identification - This option is incorrect because the Identification section is not mandatory. The Identification section is used to provide information about the program, such as the program name and author.
Option C) Procedure - This option is incorrect because the Procedure section is not mandatory. The Procedure section is used to define reusable code segments that can be called from different parts of the program.
Option D) Environment - This option is incorrect because the Environment section is not mandatory. The Environment section is used to specify file definitions and other environmental settings for the program.
The correct answer is A) Activity. This option is correct because the Activity section is the only mandatory section of an Easytrieve program, containing the main logic and processing instructions.