Which of the following methods is used to deal with soil organisms?

The method of crop rotation, resistant varieties, and chemicals is effective in managing soil organisms, particularly pests and diseases that can affect plant health and growth. Crop rotation helps disrupt the life cycles of soil-borne pathogens and pests by changing the types of plants grown in a specific area each year, which can reduce the likelihood of infestations and disease buildup in the soil.

Using resistant varieties involves selecting plant breeds that have been developed or identified to withstand specific pests and diseases, minimizing the impact of harmful soil organisms. Additionally, the application of certain chemicals—like pesticides or fungicides—can directly target harmful soil organisms to protect crops.

In contrast, daily watering and fertilization primarily support plant health but do not specifically target or manage soil organisms. Transplanting young plants is a technique for establishing plants but doesn't address the interaction with soil organisms. Natural composting can improve soil health and add beneficial microorganisms, but it doesn’t directly deal with harmful soil organisms or pests in the way that the listed methods in the correct answer do.