The main idea of a text is the point it is conveying to the reader. It can also be called the purpose for writing the text.
Okay, so this is a little hard to answer when you do not have the excerpts, but I will try my best to work a answer out of the headings. I think your answer would be C. It makes sense, the info that comes after the titles, so If I were you I would go with C.
I hope that helps.
The 2nd sentence that is highlighted in blue. “We were supposed to go to the amusement park today.”
