A developer created a trigger on the Account object. While testing the trigger, the developer sees the error message 'Maximum trigger depth exceeded'. What could be the possible causes?

User permissions control what data a user can access or actions they can perform, but they do not directly cause a 'Maximum trigger depth exceeded' error related to trigger recursion.

A 'Maximum trigger depth exceeded' error occurs when a trigger causes a change that, in turn, fires the same or another trigger too many times within the same transaction context, creating an infinite loop or exceeding the recursion limit (often 16 in Salesforce).

Whether a trigger uses a helper class or not is a code organization pattern; it does not inherently cause a 'Maximum trigger depth exceeded' error, although a helper class could contain logic that leads to recursion.

Insufficient code coverage is a metric for test quality and deployment readiness, not an error that occurs during trigger execution itself; it would prevent deployment but not cause a runtime execution error like trigger depth.