Which of the following would be considered a violation of Do Not Call Registry rules?

Calling someone who has requested not to be contacted clearly violates the Do Not Call Registry rules. When an individual has explicitly asked not to receive calls, any attempt to contact them disregards their right to opt out of marketing communications. The essence of the Do Not Call Registry is to provide consumers with a choice regarding unsolicited calls, ensuring that they can maintain control over who may contact them for marketing purposes.

The other scenarios presented do not inherently violate the Do Not Call Registry rules. Making follow-up calls to previous clients is permitted, as these individuals have already established a business relationship with the caller. Similarly, calling individuals not on the registry does not constitute a violation, as it only pertains to individuals who have opted into the Do Not Call provisions. Lastly, seeking permission to call from inquiries is a valid practice, as it respects the individual's preference and consent before any further contact is made. Thus, option A represents a clear breach of the rules governing the Do Not Call Registry.