After using the jelly on a sandwich, you close the jar and inadvertently place it on a room temperature shelf instead of in the refrigerator. when looking for the jelly a couple of weeks later and finding it on the shelf, you notice growth of a microorganism on the top of the jelly. what type of organism is likely to grow in this environment?

A fungus (mold).

Explanation:

Water activity (aw) describes the amount of water available for hydration of materials, and is a very important feature in food science, where is defined as the partial vapor pressure of pure water at the same temperature. Jellies usually have an Aw from 0.71 to 0.79. Bacteria needs at least 0.90 of water activity, and molds at least  0.7. So, based in this information, in this environment a mold is most likely to grow.