Q1. Assertion (A): In Windows, changing only the extension of a file may stop it from opening correctly in the associated programme. Reason (R): The operating system and applications often use the file extension to identify the file type and choose the linked programme.
Explanation
Both statements are true. In Windows, the visible extension is part of how a file is identified, such as .docx for Word or .xlsx for Excel. If a user changes only the extension, the file's internal content does not become a new type, but Windows or an application may try to open it with the wrong associated programme. That is why the file may not open correctly. The reason gives the mechanism behind the assertion, so option A is correct.
