Be aware that there are different types of 56K modems. But make sure your provider explicitly supports the modem that you have. This question is completely and totally irrelevant. If the site is responsible about news administration, they will accept and honor valid requests to remove groups that have become obsolete. If they just want to get the highest number possible, they won't accept such requests.
Some people have longer lists of obtuse questions.
These questions are important for the discriminating buyer of high-speed network services or for the dedicated dialup users, where connectivity and throughput are critical. But for the average dialup user, these questions are often meaningless. It's easy to get in, not so easy to get out. Ask for the provider's billing plan. The ability of a provider to answer obtuse questions on an initial sales call still may have no bearing on the quality of the service.