Which aquatic plant prefers hard water?

Coontail is the correct choice because it thrives in a range of water conditions, but it is particularly well-suited to hard water environments. This preference is attributed to its ability to absorb nutrients and minerals that are more prevalent in hard water, supporting its growth and vitality. The structure of coontail allows it to benefit from alkaline conditions, which are typically associated with harder water.

In contrast, the other options include plants that may not exhibit the same level of adaptation to hard water conditions. Bushy pondweed and leafy pondweed may prefer softer water environments, while floating-leaf pondweed typically grows in waters that are more neutral or slightly acidic. Each aquatic plant species has its distinct habitat and water chemistry preferences, which is why coontail stands out in this context.