A. Onsite Allowance element should be defined as the Payroll Relationship level element so that the element eligibility can be defined using Business Unit as the criteria.

B. You cannot meet the requirement as you cannot create element eligibility using business unit as the eligibility criteria.

C. Define the element eligibility as an Open Eligibility and create an element entry only for employees with BU2 and BU3.

D. Define multiple element eligibilities using BU2 and BU3 for Business Unit criteria.