The correct answer is: A. Has no serious occupation.
A gentleman at large is a man who has no serious occupation or responsibilities. He is often wealthy and lives a life of leisure. He may be involved in some activities, such as hobbies or philanthropy, but he does not have a regular job or career.
The other options are incorrect because they do not accurately describe a gentleman at large. A gentleman at large is not necessarily respected by everybody, nor is he necessarily held in high esteem. He may be, but it is not a requirement of the title. Additionally, a gentleman at large does not necessarily live comfortably. He may be wealthy, but he may also be poor. The only requirement for being a gentleman at large is that he has no serious occupation.