Multicellular organization — Identify the two key organizing principles that enable large multicellular organisms to function efficiently.

Introduction:
Complex organisms rely on division of labor among cells and coordination across tissues. This question tests recognition of the dual pillars that allow billions of cells to act as an integrated whole.

Given Data / Assumptions:

• Cells differentiate into specialized types (neurons, myocytes, hepatocytes, etc.).
• Intercellular communication employs chemical and electrical signals (hormones, neurotransmitters, cytokines, gap junctions).
• Prokaryotic structure is not a feature of complex animal or plant organization.

Concept / Approach:
Map each option to whether it expresses division of labor and coordinated signaling. The combination of specialization plus communication uniquely captures how multicellular systems work at scale.

Step-by-Step Solution:

Verification / Alternative check:
Physiology demonstrates endocrine and nervous coordination of specialized organs (e.g., insulin regulating specialized liver and muscle cells).

Why Other Options Are Wrong:

Common Pitfalls:
Overemphasizing a single signaling pathway and ignoring the necessity of differentiation.

Final Answer:
Cell specialization and communication between cells.