What could the last sentence of chapter 15, “This was a matter for serious consideration,” be considered? exposition
foreshadowing
Symbolism
allusion

can you put the excerpt on here then i could you

explanation:

as marlow travels down the river towards kurtz's inner station, their steamboat is attacked by african natives. interestingly, marlow notices that the natives are only shooting small arrows the size of twigs at the steamboat in an attempt to scare them away and halt their journey.

explanation:

the verbal in this sentence is an infinitive. when you want to know the reason of an action, you simply ask the question "why? ". once you know the reason you can answer with "because".

many times we don´t use the word "because" but we can use another expression and that is an "infinitive of purpose". example:

-why did your brother bring a book?

-he brought a book to study.

in the answer above you can see an example of an infinitive sentence, just like in the example of your text. "he couldn´t run fast enough to beat his older sister". so, the answer is infinitive.