Which sentence uses "although" correctly to convey the meaning of success and hard work?

The sentence that uses "although" correctly to convey the meaning of success and hard work is "Although he is very successful, he works hard." This construction correctly sets up a contrast between two related ideas: the individual's success and his continued effort in hard work.

When "although" is employed at the beginning of the sentence, it signals that despite the fact that he has achieved success, he does not rest on his laurels but instead continues to put in the effort. This shows the reader that the knowledge of his success does not negate his commitment to hard work, emphasizing the point that successful people often still need to work tirelessly to maintain their achievements or pursue new goals.

In contrast, other sentences either do not make this contrasting relationship clear or structure the thought in a way that does not effectively convey the intended meaning of perseverance alongside success. For example, a straightforward conjunction or an expression like "however" does not adequately capture the nuanced relationship "although" offers in comparing the two ideas within the same context.