Verification of truth — Essential element of a school A school always has ________.

Introduction / Context:
The prompt targets what is universally essential to a school regardless of scale, location, or modality.

Given Data / Assumptions:

• School = organized instruction for learners.
• We prioritize human and functional essentials over administrative extras.

Concept / Approach:
Contrast core instructional role (teacher) with administrative/infrastructure elements that might vary.

Step-by-Step Solution:
A teacher is indispensable for instruction and learning facilitation.A principal, library, or building are common but not strictly necessary (consider small or virtual schools).

Verification / Alternative check:
Education requires teaching; the teacher is the irreducible element.

Why Other Options Are Wrong:
They are typical but not universal.

Common Pitfalls:
Confusing common administrative structures with the core instructional requirement.

Final Answer:
Teacher