Final answer:
The sentence illustrating Agnes's challenges as a governess is one where she is shown eagerly trying to exceed expectations while also facing anger from her superior for engaging with educational material such as a newspaper.
Step-by-step explanation:
The sentence that best highlights the challenges Agnes faces as a governess, based on her position, can be found by analyzing the provided passages for scenarios that reflect the struggle of someone in a subordinate educational role within a household.
After examining the excerpts, it becomes clear that the following sentence directly addresses the challenges of being a governess:
"She was not satisfied with simply doing as well as he had commanded; she seemed anxious to do better. Nothing seemed to make her more angry than to see me with a newspaper. She seemed to think that here lay the danger."
This passage illustrates the struggles Agnes faces due to the limitations imposed on her by those in authority and their changing attitudes towards education for the governed. It succinctly encapsulates her desire to excel despite restrictions and provides direct insight into the character's predicament.