To answer this question, the user needs to understand the difference between a walkthrough and an inspection in the context of software development.

Option A states that an inspection is led by the author, while a walkthrough is led by a trained moderator. This option is incorrect because it has reversed the roles. A walkthrough is typically led by the author, while a trained moderator leads an inspection.

Option B states that an inspection has a trained leader, while a walkthrough has no leader. This option is incorrect because both an inspection and a walkthrough have a leader. In a walkthrough, the author leads the team through the software, while in an inspection, a trained moderator leads the team.

Option C is the correct answer. A walkthrough is led by the author, while an inspection is led by a trained moderator. During a walkthrough, the author guides the team through the software and explains the code and design choices. In contrast, during an inspection, the trained moderator leads the team through a formal review of the software to identify defects and potential improvements.

Option D is incorrect. Authors are typically present during both inspections and walkthroughs. In a walkthrough, the author leads the team through the software and answers questions. In an inspection, the author is available to answer questions but does not lead the review.

Therefore, the correct answer is:

The Answer is: C. A walkthrough is lead by the author, whilst an inspection is lead by a trained moderator.