<s>[INST] After reflecting on the use of AI in education,ftware developers created an AI-powered learning platform for college students. The platform utilizes machine learning algorithms to track student progress, adjust difficulty levels, and provide real-time feedback. However, the following challenges were identified:

A) Reliability of the feedback mechanism
B) Limited subject areas covered by the platform
C) Bias in machine learning algorithms
D) Limited user engagement

Considering these challenges, which would be the most critical challenge to address first?[/INST]