Which of the following methods involves the use of herbicides or plant growth regulators?

The method that involves the use of herbicides or plant growth regulators is indeed chemical control. This approach specifically employs chemical substances designed to target pests, including unwanted plants, by disrupting their growth or development. Herbicides are used to manage weeds by killing or inhibiting their growth, while plant growth regulators modify the growth patterns of plants.

In contrast, mechanical control refers to physical methods used to remove or suppress pests, such as mowing or tilling, without any chemical application. Cultural control involves practices that enhance plant health and vigor, such as crop rotation and proper irrigation, which help prevent pest issues naturally. Biological control utilizes natural predators or parasites to manage pest populations without chemicals. Each of these methods addresses pest issues in different ways, but chemical control is distinctly characterized by the use of specific chemical agents for direct action against pest organisms.