Final answer:
The most effective field for data matching is the 2)Social Security number to ensure that government employees are not receiving multiple payments.
Step-by-step explanation:
The most effective field for data matching if the auditor wants to make sure that government employees are not receiving a paycheck and a government benefit is 2)Social Security number.
This unique identifier is assigned to each individual and is commonly used for financial transactions and verifying identity. By matching the Social Security numbers of government employees with the recipients of government benefits, the auditor can identify any potential overlapping payments.