Which of the following is a common sign of termite activity?

Hollow-sounding wood is a common sign of termite activity because termites consume wood from the inside out, effectively hollowing it out while leaving the outer structure intact. This creates a void within the wood, which results in a noticeable difference in sound when the wood is tapped or knocked on. Instead of producing a solid sound, the wood will sound hollow due to the absence of material inside. Homeowners and pest control professionals often listen for this hollow sound as part of their assessment for termite infestations.

The other options do not specifically indicate termite activity. Fresh paint on walls could result from various maintenance or renovation tasks and doesn't signal any pest activity. Squeaky floorboards are typically a result of structural issues rather than pest infestations. Visible water stains generally indicate water damage and moisture problems rather than signs of termites. Therefore, hollow-sounding wood is the most direct indicator of termite presence and activity.