Who can lawyers engage in live solicitation with for pecuniary gain?

The correct choice is based on the ethical rules governing lawyer conduct, particularly with respect to solicitation. Lawyers are allowed to engage in live solicitation for pecuniary gain with individuals who have a prior relationship to the lawyer, such as fellow lawyers, family members, or previous professional clients. This is because these individuals are already familiar with the lawyer's qualifications and services, reducing the risk of coercive or misleading behavior that could arise from soliciting completely unrelated members of the public.

The rationale behind the permissiveness towards these groups stems from the idea that the solicitation does not exploit a vulnerable position or create a misunderstanding about the nature of the relationship. Therefore, engaging with these parties is considered more ethical and justifiable under the professional rules of conduct.

Other options are limited in scope. For instance, engaging only with members of the public would disregard the established professional relationships that enable informed consent and understanding. Contractual clients may be relevant, but the lack of emphasis on live solicitation limits its application. Lastly, while expressing interest in services may allow for a more amicable engagement, it doesn't encompass the broader professional relationships that make option C the most encompassing and appropriate choice regarding live solicitation by lawyers.