Which of the following is NOT a method for controlling pests without using pesticides?

The correct choice is based on the idea that controlling pests without pesticides focuses on non-chemical methods. Random spraying of chemicals in gardens is inherently a chemical approach and thus does not align with methods aimed at minimizing or eliminating pesticide use. This method would likely lead to environmental harm, unintended effects on non-target organisms, and potential harm to the applicator through exposure to chemicals.

In contrast, the other options are all recognized methods for managing pest populations without resorting to chemical pesticides. Biological control leverages natural predators or parasites to keep pest populations in check. Mechanical methods, such as traps or physical barriers like screens, directly prevent pests from accessing plants. Genetic modification of plants can enhance resistance to pests through changes in the plant's genetic makeup, allowing them to thrive without the need for chemical interventions. These strategies support sustainable agriculture and environmental health by focusing on integrating natural processes into pest management.