Which of the following statements describes the feeding habits of parasites?

The correct statement highlights that parasites typically live and feed off another organism, known as the host. This relationship is crucial to their survival, as parasites derive nutrients and energy from their host, which can lead to harmful effects for the host organism. This feeding habit is a defining characteristic of parasites; they adapt to living in or on their host and often depend on them for sustenance.

Other statements do not accurately reflect the nature of parasites. The mention of external reproduction does not apply to all parasites since many reproduce internally within their hosts. The statement about exclusively feeding on plants is inaccurate because some parasites, like certain types of worms and protozoa, feed on animals. Lastly, the assertion that they thrive in all environments equally is misleading; parasites often have specific environmental requirements and are adapted to particular host organisms, indicating that their success is context-dependent rather than universally applicable.