Final answer:
The author's book is selling well, and (b) they are using free lectures as a promotional strategy while expressing gratitude for the support they're receiving.
Step-by-step explanation:
The conversation suggests that the author's book is indeed selling well, as it is described as "selling like hotcakes," which is a colloquial expression for selling very quickly or in large quantities. The author is employing a promotional strategy that involves delivering free lectures on their website, which serves to promote the book directly to the public.
Furthermore, the conversation reveals that the author is very grateful for the support received, as the author thanks the other person and expresses how much their help means. This exchange highlights the importance of personal networks in promoting a product and the value that authors, such as the one mentioned in the passage, may place on educational impact over commercial gains.