Which of the following statement about the effects of diseases on crops are true? Reduction in I. quality of products II. photosynthetic ability III. cost o...

The statement that is true about the effects of diseases on crops is that they lead to a reduction in the quality of products (I), a reduction in the photosynthetic ability (II), and a reduction in the yield of the produce (IV). Crop diseases can cause discoloration, spots, and other blemishes that lower the market value of the crop. They can also interfere with the plant's ability to perform photosynthesis, which reduces its growth and productivity. Moreover, some diseases can cause the plant to wither or die, which ultimately reduces the yield of the crop. While diseases may not necessarily increase the cost of production (III), they can still have a significant economic impact by reducing the quantity and quality of the produce. Therefore, the correct option is I, II, and IV only.