Which pesticide characteristic increases the potential for groundwater contamination?

High solubility is the correct choice because it is a key characteristic that increases the potential for groundwater contamination. When a pesticide has high solubility, it means that it can dissolve easily in water. This property allows the pesticide to move more readily through the soil and into groundwater, particularly during rain events or irrigation. As the pesticide dissolves, it can leach into the water table, posing a risk of contaminating drinking water sources.

In contrast, low volatility would indicate that a pesticide is less likely to evaporate and enter the atmosphere, thus reducing the likelihood of airborne transport or drift, which is not directly related to groundwater contamination. High persistence means that the pesticide remains active in the environment for an extended period. While this can be a concern for soil and surface water, it does not inherently relate to the ability to contaminate groundwater as directly as solubility does. Low toxicity refers to the harmful effects of the pesticide on humans, animals, or the environment but does not impact its potential to leach into groundwater. Therefore, high solubility is the most significant factor in increasing the risk of groundwater contamination.