Answer:
a fungus
Step-by-step explanation:
Fungi is any group of eukaryotic organisms , and examples are yeast, molds and mushrooms.
They are known to be common in the environment, because they can live in the air, soil, water and plants. And they are known to grow best or thrive under a warm condition.
They are classified into four divisions , they include
* Chydridiomycota
* Zygomycota e.g bread mold
* Ascomycota e.g Yeast
* Basidiomycota e.g club fungi
In this case, the organism that will be noticed on the jar after several weeks will be a fungus, because , the mold is a type of fungus that feed saprophitically on food substances. Also the fungus grow best in a warm temperature.