Which method involves directly killing a pest or making its environment unsuitable?

The method of control that involves directly killing a pest or making its environment unsuitable is best identified as mechanical and physical control. This approach focuses on the use of physical barriers, traps, or manual removal of pests. For example, using traps to catch insects or employing techniques such as tilling the soil to disrupt the lifecycle of pests demonstrates this method's direct action on pests.

This method is effective because it doesn't rely on chemicals or biological agents but instead uses physical means to achieve pest control, resulting in immediate effects. While other methods such as chemical control involve the application of pesticides to kill pests, and biological control involves the use of natural predators or pathogens to manage pest populations, they do not represent the direct removal or alteration of the pest’s living conditions in the same immediate manner as mechanical and physical control does. Cultural control, on the other hand, focuses on altering farming practices or planting techniques to make the environment less conducive to pests, rather than directly killing the pests themselves.