Standardization, particularly in telecommunications by bodies like 3GPP and ETSI, is fundamental for creating an interoperable, multi-vendor ecosystem. The process involves decomposing a complex network architecture into a set of discrete, defined functional elements (e.g., Network Functions in 5G). Each element has a specified purpose and set of capabilities. To ensure these elements can communicate and work together regardless of the vendor, standardization provides well-defined interfaces (or reference points) between them. These interfaces have rigorously specified protocols, data models, and procedures, forming a common language for all network components.

B. Flexible rules open to interpretation.

This is the opposite of standardization's goal; standards aim to be precise and unambiguous to prevent interoperability issues.

D. Simplicity for the implementation.

While standards provide a clear blueprint, implementing them, especially for complex systems like 5G, can be extremely challenging and is not inherently simple.

1. 3GPP TS 23.501, "System architecture for the 5G System (5GS)" (V17.7.0, 2022-12):

Section 4.2, "Architectural reference model": This section explicitly defines the standardized Network Functions (NFs) that constitute the 5G architecture (supporting option C). The diagrams and descriptions show the "reference points" (e.g., N1, N2, N11) which are the well-defined interfaces between these NFs (supporting option A).

2. ETSI GS NFV 002, "Network Functions Virtualisation (NFV); Architectural Framework" (V1.2.1, 2014-12):

Section 4, "NFV Architectural Framework": This section describes the main functional blocks of the NFV framework, such as the VNF, NFVI, and MANO. This is a clear example of defining functional elements (supporting option C).

Section 5, "Reference Points": This section details the reference points (e.g., Vi-Vn, Vn-Nf), which are the standardized interfaces between the functional blocks, ensuring interoperability (supporting option A).

3. Nokia, "The 5G Core: A Nokia white paper," 2020:

Page 5, "Service-based architecture": The document states, "The 3GPP has defined the 5G Core according to cloud-native principles and a Service-Based Architecture (SBA). The SBA is composed of a set of interconnected Network Functions (NFs)... NFs provide services to other NFs through well-defined interfaces." This official vendor document confirms that standardization provides both defined functional elements (NFs) and well-defined interfaces.