Crop yields can decrease due to biotic and abiotic stresses in various conditions. Which of the following factors is/are classified as abiotic stress?

Correct option is B

Abiotic stresses are caused by non-living environmental factors like temperature, drought, frost, salinity, etc. Frost, being a temperature-related factor, is classified as abiotic, affecting physiological processes in plants.
Explanation of options: (a) ✘ Insects are living organisms and hence considered biotic stress. (b) ✔ Frost is a non-living environmental factor and hence abiotic in nature. (c) ✘ Nematodes are microscopic worms and fall under biotic stress. (d) ✘ Diseases are caused by pathogens (living organisms), thus biotic.