Final answer:
The organism found by Nathan on the rotting log is most likely a fungus-like organism because it is a eukaryote with a cell wall that does not photosynthesize but instead decomposes organic matter.C. fungus-like
Step-by-step explanation:
On a trip to a wildlife sanctuary, Nathan found a piece of rotting log and took a sample to examine in his laboratory. Given that the organism found was eukaryotic, could not photosynthesize, and had a cell wall, the most likely type of organism feeding on this sample would be C. fungus-like. Fungi are eukaryotic decomposers or saprotrophs that feed on dead organic matter by secreting digestive enzymes and digesting it externally. This is consistent with an organism feeding on a rotting log, as fungi are the only organisms that can decompose wood due to the production of enzymes necessary to break down cellulose and lignin.