Answer:
Adware
Explanation:
Based on the information provided within the question with regards to the situation at hand it seems that the program on Sarah's system is Adware. This is software that shows pop-up advertisements to the user within the user interface of a software, which generates revenue for the advertising company supporting it. In which many cases the software acts like a computer virus bypassing a systems security and auto installing on a piece of hardware. like what happened to Sarah.