Correct option is A
The correct option to fill in the blank is (a) Diligent.
Explanation: "Diligent" means hardworking and careful, which logically leads to prosperity.
Meanings of other options:
· Inactive: Lacking action, opposite in meaning to what the sentence suggests.
· Indolent: Lazy, not associated with prosperity.
· Lethargic: Sluggish or lacking energy, inappropriate for this context.