Consider the situation below and analyze the following sentences:

Sarah has a daughter. Her name is Martha, and she is ten years old. Every day she goes to school. She stays there from 9 a.m. to 3 p.m. She’s at school now. Today Martha’s mother wants to speak to her daughter’s teacher. So she has gone to the school to see her. She’s at the school now.

I. We say Martha “goes to school” and “is at school” because we are not thinking of a specific school.

II. We say Martha’s mother “has gone to the school” and “is at the school” because we refer to a specific building (Martha’s school).

III. We say Martha’s mother “has gone to the school” and “is at the school” because we refer to one of many schools (Martha’s school).

Which ones are correct?