Why is hard water considered more beneficial for plant growth than soft water?

Hard water is considered more beneficial for plant growth primarily because it has a higher concentration of calcium and magnesium. These two minerals are essential nutrients for plants and play a critical role in various physiological processes. Calcium is important for cell wall structure and stability, while magnesium is a vital component of chlorophyll, which is essential for photosynthesis. The presence of these minerals in hard water helps to improve soil fertility and provides plants with the necessary elements to thrive and grow strong.

In contrast, while other choices might contain some elements that could affect plant growth, they do not specifically address the beneficial role of the minerals found in hard water. Thus, the increased availability of calcium and magnesium in hard water directly supports healthier plant development.