Final answer:
The last observed element in an AMOS (Augmentable Main Overlay Structure) is the element that is last added to the augmented data structure.
Step-by-step explanation:
When augmenting an AMOS, the last observed element is the element that is last added to the augmented data structure. The AMOS (Augmentable Main Overlay Structure) is a data structure that allows for easy insertion and deletion of elements. It can be implemented using various data structures such as arrays or linked lists. When adding elements to the AMOS, the last element added will always be the last observed element.