Final answer:
To address multiple issues in a chat application's version 1.0, the company should release either a patch or an update, which will provide a comprehensive fix that may include improvements and new features along with bug fixes.
Step-by-step explanation:
To address multiple issues reported by users over a chat application's version 1.0, the company should release a patch or an update. Patch usually refers to a small fix that resolves specific issues or bugs, while an update can include more comprehensive improvements to performance, security, and new features alongside bug fixes. The term upgrade typically refers to a significant improvement that often includes a change in the version number and may not be solely focused on fixing current version issues. On the other hand, a bug fix is a correction for a single issue within the application. However, since multiple issues need to be addressed, a patch or update would be more comprehensive solutions.