The definition to parasitism is "the practice of living as a parasite in or on another organism." (Wikipedia). Therfore the answer to this is Ticks live on and drink blood from a cow, because this is the only option where an organism is living directly off another organism.
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The answer to the following question is D) They reproduce quickly and take up little space
Answer: c. Gizzard
Explanation:
The Gizzard or ventriculus is the part of the digestive system of the aves, which acts as a mechanical stomach. It is composed of two sets of muscles that act as a avian teeth. It also posses the thick lining that protects those muscles. The gizzard facilitates the mechanical break down of the food as may be caused by the teeth.