A plant which grows on another without causing harm to the host plant is called...

Explanation

The question is asking for the name of a plant that grows on another plant without causing harm to the host plant. This type of plant is called an epiphyte. Epiphytes are plants that grow on other plants, usually trees, but they do not harm the host plant. Instead, they use the tree or other plant as a support structure to grow towards the sunlight. Epiphytes are common in rainforests where there is a lot of moisture in the air and on the tree trunks. They can also be found in other types of forests and even in gardens. It is important to note that epiphytes are not parasites, which are plants that grow on other plants and harm them by taking nutrients from them. For example, mistletoe is a parasitic plant. It grows on trees and takes nutrients and water from them, which can harm the tree. On the other hand, epiphytes do not harm the host plant. Saprophytes, another option listed in the question, are plants that obtain nutrients from dead or decaying organic matter. They are important in recycling nutrients in ecosystems. Predators and prey, the other options listed, are not relevant to this question as they refer to animals that hunt and are hunted in food webs. In conclusion, the correct answer to this question is Option C: an epiphyte, which is a plant that grows on another plant without causing harm to the host plant.