The correct answer is option-1: Mercury. Biomagnification is the process by which certain substances, such as heavy metals, become more concentrated and increase in toxicity as they move up the food chain. Mercury is one of the main contributors to the biomagnification problem in ecosystems. It is a highly toxic metal that can enter the environment through various sources such as industrial waste, coal-fired power plants, and mining activities. Once in the environment, mercury can be converted into methylmercury, a highly toxic form that can accumulate in the tissues of organisms. As smaller organisms are consumed by larger ones, the concentration of methylmercury increases, resulting in biomagnification. This is particularly concerning because mercury can have detrimental effects on the reproductive, neurological, and immune systems of animals, including humans. It is important to minimize the release of mercury into the environment to prevent further biomagnification.