The speaker in "invictus" asserts that "the menace of the years/ Finds and shall find me unafraid." The speaker in "A Rainy Day" reminds himself that "into each life some rain must fall." based on this word choice in speakers in both the rainy day and invctus are struggling to maintain:

AFinancial advantage.
BThe love of a good woman.
CDiscouragement and despair.
DA hopeful spirit.