Which of the following is an environmental method of managing pests?

The environmental method of managing pests focuses on utilizing natural processes or methods that minimize harm to the ecosystem. In the context of pest management, cleaning up spills, such as liquor, can prevent pest attraction by eliminating a food source. This method helps maintain a clean environment, which is essential for controlling pest populations. Addressing potential breeding grounds or attracting factors is a critical strategy in integrated pest management.

The other options involve more direct interventions in pest control. Using fungi to kill pests can be seen as a biological control method, which, while environmentally based, is more aggressive than simply maintaining cleanliness. Vacuuming to remove fleas is a mechanical method, directly removing the pests, and applying a growth regulator represents a chemical approach to pest management, modifying the developmental processes of insects rather than addressing environmental factors.