Chlorosis is best described as which phenomenon?

• A. Movement of soil components, especially topsoil
• B. Yellowing of leaves due to magnesium or zinc deficiency
• C. A chemical intended to kill insects
• D. An abbreviated safety data sheet

Answer: (D)

Chlorosis is the yellowing of leaves caused by a reduction in chlorophyll, the pigment that gives leaves their green color. This yellowing often results from a deficiency or imbalance of nutrients that are needed to make and maintain chlorophyll. In horticulture, magnesium is a common culprit; when magnesium is lacking, older leaves typically turn yellow between the veins as chlorophyll production drops. Zinc can also cause pale, distorted leaves with yellowing, especially in younger growth. So, describing chlorosis as yellowing of leaves due to magnesium or zinc deficiency aligns with the way nutrient shortages disrupt chlorophyll and produce that yellowing symptom. The other options describe soil movement, a pesticide, or a safety data sheet, which are unrelated to chlorosis.