Which of the following describes a marketable lead?

A marketable lead is defined as a lead that has the potential to receive marketing communications and engage with them. The correct choice identifies a lead with an email address that is not blacklisted, which means the lead can be contacted for marketing purposes. If a lead's email address is not blacklisted, it indicates that the lead has not previously opted out of receiving communications or engaged in any activity that would classify them as undeliverable or unresponsive.

On the other hand, a lead with an invalid phone number lacks a fundamental means of communication, making them less marketable. Similarly, a lead unsubscribed from email communications or has opted out of marketing communications cannot receive any marketing messages, making it impossible to consider them marketable. The focus on being allowed to reach out via the indicated email is essential in determining the marketable status of a lead, aligning with the definition of engagement in marketing practices.