If plants in several different plant families are affected by symptoms, the cause is most likely to be:

• A. Fungus
• B. Virus
• C. Nematode
• D. Abiotic factor

Answer: (D)

When many plants from different families show the same symptoms, it points to a non-living stress affecting a broad range of species rather than a specific pathogen. Living pests like fungi, viruses, or nematodes usually have some host preference and don’t typically cause identical problems across such diverse plant groups. Abiotic factors—environmental stresses or chemical injuries such as drought, nutrient imbalances, pH or salinity problems, temperature extremes, or exposure to herbicides or pollutants—tend to produce similar symptoms in a wide variety of plants. So the most likely cause is an abiotic factor.