Passage Summary: An economist provides specific rules for when a tax is working well and when it is failing based on money earned, who pays it, and how much it costs to manage.

Reasoning: A tax is defined as effective if it both generates revenue and hits its intended targets; it is defined as ineffective if it fails to generate revenue and is costly to enforce.

Analysis: This is a formal logic exercise where we must strictly apply the economist's definitions. To prove a tax is 'effective,' you must satisfy two conditions: revenue generation and precise targeting. Conversely, to prove a tax is 'ineffective,' you must show it both lacks revenue and has high enforcement costs. Look for an answer choice that acts as a valid deduction from these conditional statements, being careful not to assume that a tax failing one 'effective' criteria automatically makes it 'ineffective' by the economist's specific definition.