The right flower is a young flower. Old flowers are already wilted, so they're not right for this occasion.
young person ★★★☆☆ KUNKUN 若 (young) + 者 (professional) = 若者 (young person)
young person - example of the kunyomi (もの) suffix
somewhat ★☆☆☆☆ 若 (young) + 干 (dry out) = 若干 (somewhat)