Verification of truth — Essential part of a book A book always comprises ________.

Introduction / Context:
In classic reasoning keys, a physical “book” is a bound set of pages. Digital formats are excluded unless specified.

Concept / Approach:
Pick the structural element that defines a physical book.

Step-by-Step Solution:
“Pages” are essential to the physical artifact.“Lessons” and “Figure” are content types, not mandatory in all books.“Content” is abstract; the test favors the concrete structural invariant.

Final Answer:
Pages