Which of the following are the three factors in the disease triangle?

The correct answer emphasizes the critical components that contribute to the development and severity of plant diseases, known as the disease triangle. This triangle consists of three key elements: a susceptible host plant, a pathogen, and the necessary environmental conditions that favor disease development.

When these three factors come together, the likelihood of a disease outbreak increases significantly. The susceptible host plant provides the necessary biological material for the pathogen to infect, while specific environmental conditions—such as temperature, humidity, and moisture—create an ideal setting for the pathogen to thrive and reproduce. Understanding this interaction is essential for effective disease management and implementing control measures in agriculture.

The other options highlight various factors relevant to plant health and growth but do not accurately represent the core components of the disease triangle. For example, weak soil, moisture, and temperature influence plant health and growth but do not specifically identify the pathogen or host dynamics. Proper watering, fertilizer type, and sunlight exposure pertain more to plant cultivation practices rather than the specific interactions that lead to disease. Finally, plant species diversity, soil quality, and pest variety are important aspects of ecosystem health but do not define the essential triad of factors necessary for the expression of a specific plant disease.