It sounds like the behavior of your Option key has changed unexpectedly. Here are a few things you can try to resolve this issue on your Mac:
1.Check Keyboard Settings:
Open System Preferences and go to Keyboard settings. Click on the Keyboard tab, then check the settings for Modifier Keys in the Keyboard shortcuts. Make sure the Option key is set to its default behavior.
Also, you can explore other options to ensure no new key bindings or shortcuts have been assigned that might be interfering with the usual behavior.
2.Reset Keyboard Preferences:
Sometimes, corrupt preferences files can cause unexpected keyboard behavior. Resetting them might help:
Close any open applications. Open Finder, and go to Library/Preferences/.
Find and move files related to keyboard settings (like com.apple.keyboardtype.plist or any other similar files) to the desktop or another folder for backup.
Restart your Mac. This will reset keyboard preferences to default, and new preferences files will be created. If this fixes the problem, you can delete the old files. If not, you can restore them from your backup.
3.Inspect Accessibility Settings:
Sometimes, accessibility settings might alter how the keyboard behaves:
Go back to System Preferences and select Accessibility.
Check options under Keyboard to see if any settings might be affecting the Option key's behavior.
4.Check for Software Conflicts:
Consider if you've recently installed any new software that could be interfering with keyboard inputs. Sometimes, applications can alter or override default key functions.
Temporarily disable or uninstall recent software to see if that resolves the issue.