Passage Summary: We can learn about history by looking at the world today, but the older the history, the harder it is to use today's world as a guide.

Reasoning: Current environmental and physical conditions provide evidence of the past, but the reliability of this evidence decreases as the time period being studied becomes more remote.

Analysis: This stimulus describes an inverse relationship between the passage of time and the utility of current evidence. To match this principle, look for an answer choice where a specific tool or method is effective for recent or nearby events but loses its effectiveness as the subject becomes more distant. The logic is essentially a 'diminishing returns' model based on chronological distance.