Which of the following associations can upset the balance of nature?

The association that can upset the balance of nature is parasitism. Parasitism is a relationship between two organisms, where one benefits (the parasite) and the other is harmed (the host). The parasite obtains its food and shelter at the expense of the host, often causing damage or even death. This relationship can upset the balance of nature by reducing the population of the host species, disrupting food chains and ecosystems, and even leading to the extinction of certain species. Epiphytism, symbiosis, and saprophytism are all natural associations between different organisms that play important roles in the ecosystem, but do not necessarily upset the balance of nature. Epiphytism is a type of commensalism where one plant grows on the surface of another plant for support, without harming it. Symbiosis is a relationship where two different species live together in a mutually beneficial relationship, such as the partnership between pollinators and plants. Saprophytism is a type of heterotrophic nutrition in which an organism obtains its food by decomposing dead organic matter. Therefore, the association that can upset the balance of nature is parasitism.