Concept:A relationship in which one organism benefits while the other is harmed is called parasitism.
Explanation:Saprophytism involves feeding on dead and decaying matter.
Commensalism is a relationship where one organism benefits and the other is neither helped nor harmed.
Mutualism is a relationship where both organisms benefit from each other.
Parasitism is a relationship where one organism, the parasite, gains nutrients at the expense of the host.
The host loses resources and may be harmed or weakened.
Therefore, the type of association that matches one gaining and the other losing is parasitism.
Answer:D. parasitism