What ingredient is used in a flushing solution to irritate pests?

The correct choice is lemon scented dishwashing detergent, as it serves as an effective ingredient in a flushing solution designed to irritate pests. The surfactants present in dishwashing detergents reduce the surface tension of water, allowing the solution to spread more effectively. When combined with its lemon scent, which can be repellent to some pests, it aids in flushing them out from their hiding places.

While other ingredients like white vinegar, vegetable oil, and fabric softener may have specific uses in pest management, they do not have the same practical attributes as lemon scented dish soap when it comes to creating an effective flushing solution. For instance, white vinegar is more commonly used for its acidity which can deter pests, but it does not act as a surfactant. Vegetable oil is generally used for suffocation rather than irritation and does not contribute to flushing pests out. Fabric softener, while it can be used in some mixtures for similarities to detergents, does not have the same pest deterrent properties. Therefore, lemon scented dishwashing detergent is particularly effective in this context for its dual function in irritation and flushing out pests.