Sometimes it's good to be unhappy is the correct answer.
Explanation:
A rainy day is a poem written in three stanzas of five lines each. The speaker compares the rainy day with his own feelings and past situations and the excerpt belongs to the las stanza.
Letter A is the correct option because of the phrase "some rain must fall", understanding the rain as a metaphor of unhappiness, which is not totally bad as long as it does not turn into something that happens everyday. Also, as we can see in the next line, "the sun is still shining" which could be understood as part of a brighter future and coming back to happiness to keep balance.
