How do reference resources help improve vocabulary?

It helps you understand the info. and if you understand it you can use words that you know make sense with the topic. (I think)Explanation:

hello,

your answer is a) the metaphor suggests that the poetic themes are serious and dark.

collins is comparing the poem to a dark room. he is suggesting that the poems theme is serious and wants you to understand it. you don't need to understand the poet in order to understand the poem. you also don't need to move around while reading it. he is simply saying the poem has a dark and serious theme.

- i.a -