An allowance plan has adefault value of $100 USD.

The correct way to localize allowance amounts in Workday without impacting other populations is through the use ofplan profiles. Plan profiles allow administrators to definecountry-specific or location-specific valuesusing eligibility rules, ensuring that employees automatically receive the correct amount during hire and other staffing events.

In this scenario, adding anew plan profile for Irelandwith a value of€90 EURensures that employees hired in Ireland automatically receive the correct allowance. This approach preserves the existing default value of $100 USD for employees in the US and avoids unintended downstream impacts.

Updating the default value would affect all employees who do not meet profile eligibility, including US employees. Allowance Plan Adjustments are used to update existing assignments, not to control defaulting logic during hire. Manual compensation changes are inefficient, error-prone, and contradict Workday best practices for scalable configuration.

Therefore, adding anew allowance plan profile for Irelandis the correct, controlled, and Workday-recommended solution, making option C the correct answer.