I'd say that 'every' is the adjective you are looking for. It specifies the noun 'light'.
The correct answer for this question would be the third option. The novel's setting on an uninhabited island affects the boys' behavior in the first few chapters of the novel which <span>causes them to ignore socially polite behavior as they face the dangers of the wild. Hope this answer helps.</span>
I think it’s ethos since the doctor is a credible sources due to them being an expert and doctor.