Passage Summary: Frogs dry out easily, especially small ones. Since the northern Yucatán is dry and the southern part is wet, moisture is the main thing deciding where frogs can live there.

Reasoning: Frogs have permeable skin making them prone to dehydration, and small frogs specifically lack the body-mass-to-skin ratio to survive in dry areas; the Yucatán's climate varies from arid in the north to wet in the south.

Analysis: This stimulus provides a set of biological constraints and a geographical layout. We are told that small frogs cannot survive in arid climates and that the northern part of the peninsula is arid. Therefore, we should look for an answer that concludes small frogs are likely restricted to the southern, wetter regions of the Yucatán. The logic here is a straightforward application of a general rule to a specific location.