Why Do the Authors Recommend That Teachers Include Extensions and Differentiations

Why do the authors recommend that teachers include extensions and differentiations in their lesson plans?

A) To address the needs of students whose abilities differ from those of "average" students.
B) To plan for unexpected events or unanticipated stumbling blocks.
C) To clarify the main goals of the lesson for students.
D) To determine how well students have internalized new information.