How does the girl express her feelings about the school trip?

The girl expresses her feelings about the school trip by stating that it was boring. This choice indicates that her experience was not engaging or interesting, which directly conveys a negative perspective on the trip. When someone describes an experience as boring, it reflects a lack of stimulation or excitement, suggesting that the activities did not hold her attention or provide enjoyment.

In contrast, the other responses suggest positive or neutral feelings about the trip. Saying it was enjoyable or fascinating indicates that she found the trip pleasant or intriguing, while describing it as tiring implies exhaustion but could still suggest that the trip had worthwhile moments. Therefore, the choice of "boring" succinctly captures her dissatisfaction and disinterest in the school trip, making it the correct expression of her feelings.