In parasitism, what happens to the host organism?

In a parasitism relationship, the host organism is harmed by the parasite. Parasitism involves one organism, the parasite, benefiting at the expense of the host. The parasite typically derives nutrients or other benefits from the host, often leading to stress, disease, or harm to the host's health. This harm can manifest in various ways, such as reduced growth, reproduction issues, or even death in severe cases.

The other options do not accurately reflect the nature of parasitism. The host does not benefit (as stated in the first choice) because the fundamental characteristic of parasitism is that it is detrimental to the host. Additionally, the host is not left unaffected; rather, it experiences adverse effects due to the parasite’s exploitation. Lastly, the host does not thrive equally in a parasitic relationship, which contradicts the basic dynamics of parasitism. Therefore, option C best describes the impact of parasitism on the host organism.