See I got this topic once and got an 'F'. Know why? Because it said 'an island'
THERE ARE ISLANDS THAT ARE INHABITED PEOPLE! Cuba, Hawaii, the Florida keys, Haiti, Dominican Republic, Japan, Thailand, just to name a few. I thought it was 'creative' and 'original' but nooo. I 'didn't follow the prompt' and deserved that 'F'.
Although I agree that your idea was quite original and that the prompt should've made it clear that it was a "deserted island", it was probably the teachers intention for his/her students to write what they would do in order to survive; since you went the clever route and basically placed yourself on a populated island and could easily seek help, it wasn't exactly displaying the actions you would take in the event that you were in peril. TL;DR - it didn't deserve an F, but keep in mind that teachers have their own interpretations of the prompts.
If she wanted for me to write about a deserted island she should've put 'Deserted island' which she didn't. It was her fault she didn't make it clear that she wanted 'deserted island' over just 'island'.
THERE ARE ISLANDS THAT ARE INHABITED PEOPLE! Cuba, Hawaii, the Florida keys, Haiti, Dominican Republic, Japan, Thailand, just to name a few. I thought it was 'creative' and 'original' but nooo. I 'didn't follow the prompt' and deserved that 'F'.