Which of the following is a sign that mold may be present?

Visible water damage is a strong indicator that mold may be present. Mold thrives in damp, humid environments, and any evidence of water damage—such as discoloration, stains, or warping on walls, ceilings, or floors—can suggest an ongoing moisture issue that facilitates mold growth. The presence of water damage often means that there has been a leak or excess moisture that could lead to mold colonization if not addressed promptly.

Increased ventilation, while beneficial for reducing moisture levels, does not directly indicate that mold is present. Cold interior walls can be a symptom of inadequate insulation or poor heating rather than an indication of mold, and regular maintenance checks, although important for overall building health, do not specifically point to mold presence. Thus, visible water damage stands out as the most telling sign of potential mold issues.