Aworker was sitting at her cubicle in the middle of a large room during her lunch break. she began peeling the orange she brought to eat. at first, only she could smell the aroma. but in a matter of minutes, those in the nearby cubicles could also smell it. after several more minutes had passed, nearly everyone in the room could smell the orange. what best explains how so many people could smell one small orange in the middle of a large room?

The correct answer is simple diffusion. 

Simple diffusion refers to the process whereby particles or molecules move across a concentration gradient (from high to low concentration) without any aid from other sources. In this instance, everyone in the room could gradually smell the orange because the smell of the orange diffused across a concentration gradient (from a high concentration- where the worker peeled the orange- to a low concentration).