Consider the following : 1. Birds 2. Dust blowing 3. Rain 4. Wind blowing Which of the above spread plant diseases ?

Option (d) is correct because plant pathogens—including fungi, bacteria, and viruses—are dispersed through both biotic vectors like birds and abiotic environmental factors such as wind, rain (via splash dispersal), and dust particles. While candidates might overlook "dust blowing" or "rain," dust can transport dormant spores over vast distances, and rain is a primary driver for the localized spread of soil-borne pathogens to plant surfaces. The core concept tested is the mechanism of pathogen dispersal and the role of diverse environmental agents in the plant disease cycle.