Answer: understate the economy's performance (A)
Step-by-step explanation:
The underground economy are the economic transactions that are seen to be illegal because the goods or services that are traded are unlawful in nature, or non-compliance of the transactions with governmental requirements. Examples of activities involved in underground economy are tax evasion, smuggling etc
When the underground economy is sizable, it will have an effect on the gross domestic product as there will be an understatement in the performance of the economy since such activities are not included in the GDP.