Verification of truth — Essential presence in a hospital A hospital always has ________.

Introduction / Context:
The question asks for an essential, universally present feature of a hospital.

Given Data / Assumptions:

• A hospital provides medical diagnosis, treatment, and care.
• We seek a must-have constituent across contexts.

Concept / Approach:
Between staff categories and infrastructure, which is indispensable to the definition?

Step-by-Step Solution:
Doctors are requisite for medical decision-making, diagnosis, and procedures—core hospital functions.Nurses are fundamental in most hospitals, but some minimal clinics (mis-termed as “hospitals” in puzzles) could theoretically emphasize the presence of a doctor over staffing breadth.A “room” and “telephone” are infrastructural conveniences; not definitional in reasoning keys.

Verification / Alternative check:
The absence of physicians would essentially negate hospital functions; thus “Doctor” is the safest invariant.

Why Other Options Are Wrong:
Rooms/telephones are common but not definitional; nurse availability, while critical, is treated as supportive in such puzzles.

Common Pitfalls:
Equating common features with definitional necessity.

Final Answer:
Doctor