Lily arrives at Carmelita's house so they can walk to school. When Carmelita sees Lily's science notebook in her partially opened backpack, Carmelita rushes back into her house to retrieve her own notebook, which contains an assignment that is due that day. Carmelita's sensation upon seeing Lily's notebook became a perception. This triggered Carmelita's:

The answer is working memory.

Explanation:

Working memory is a memory system responsible for holding short-term information which is available for manipulation. In the example, Lily could manipulate the visual information of Carmelita's notebook, and in turn remember to take her own.

Other tasks which involve working memory are using a mathematical formula to solve a problem or repairing a device after reading a manual.