SNMPv3 was specifically designed to address the significant security weaknesses of SNMPv1 and SNMPv2c. Its architecture is built around a modular framework that introduces robust security and enhanced administration capabilities.

Security: SNMPv3's User-based Security Model (USM) provides message integrity (preventing tampering), authentication (verifying the source), and encryption (ensuring privacy of the data). This is a major enhancement over the clear-text community strings used in earlier versions.

Administration: SNMPv3 provides a more flexible administrative framework, including the View-based Access Control Model (VACM), which allows for granular control over which users can access which parts of the Management Information Base (MIB). The concepts of notification originators and proxy forwarders are also integral parts of this advanced administrative structure.

A. SNMPv2c: This version still relies on the insecure community-string-based security model from SNMPv1. It does not offer authentication or encryption.

B. SNMPv1: This is the original version and has the most basic security, using only a clear-text community string for access, which provides no real security.

D. SNMPv2: This refers to the collection of standards that includes SNMPv2c. Like SNMPv2c, it lacks the security features described in the question.

1. Huawei. (2020). HCIA-Datacom V1.0 Training Material (H12-811). Section: Network Management and O&M, Subsection: SNMP Versions. "SNMPv3 provides encryption and authentication functions based on the User-based Security Model (USM) and access control functions based on the View-based Access Control Model (VACM). It is the most secure version."

2. Blumenthal, U., & Wijnen, B. (Eds.). (2002). RFC 3411: An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks. IETF. This document provides an overview of the SNMPv3 architecture, explicitly detailing its focus on security and administration.

3. Wijnen, B., Presuhn, R., & McCloghrie, K. (Eds.). (2002). RFC 3414: User-Based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3). IETF. This RFC specifies the security model for SNMPv3, detailing the mechanisms for authentication and privacy (encryption).