Which of the following can indicate the presence of a pest problem?

The presence of visible damage on plants is a strong indicator of a pest problem. When pests infest plants, they often cause noticeable harm that can manifest in various ways such as chewed leaves, discoloration, wilting, or stunted growth. These symptoms are direct effects of pest activity, highlighting their presence and indicating that the plants are under stress due to insect feeding or damage.

The other options may suggest some form of stress or environmental issue but do not specifically point to a pest infestation. Decreased soil moisture may indicate poor watering practices or drought conditions, while weak root growth can be caused by various factors including poor soil quality or overwatering. Increased sunlight exposure, although it can affect plant health, does not directly correlate with pest activity. Therefore, visible damage on plants serves as the most direct and clear indication of a pest presence.