The most significant aspect of the GDPR ensuring consistent implementation is its legal form as a Regulation. Under EU law, a Regulation is directly applicable and binding in its entirety across all Member States without requiring national transposition. This creates a single, harmonized set of data protection rules throughout the EU. This contrasts sharply with its predecessor, Directive 95/46/EC, which set out goals but allowed Member States to implement them through their own national laws, leading to significant fragmentation and inconsistency across the Union. The choice of a Regulation was a deliberate act to remedy this fragmentation and establish a uniform legal framework.

A. That it essentially functions as a one-stop shop mechanism This mechanism harmonizes enforcement for cross-border processing by a lead authority, but it does not create the consistent law itself.
C. That it makes notification of large-scale data breaches mandatory This is a specific, harmonized obligation within the GDPR, but it is only one component, not the foundational reason for the consistent implementation of the entire law.
D. That it makes appointment of a data protection officer mandatory Similar to breach notification, this is a specific, harmonized rule for certain entities, not the overarching legal instrument that ensures EU-wide consistency.

1. Official Journal of the European Union, Regulation (EU) 2016/679 (GDPR), Recital 10: "In order to ensure a consistent and high level of protection of natural persons and to remove the obstacles to flows of personal data within the Union, the level of protection of the rights and freedoms of natural persons with regard to the processing of such data should be equivalent in all Member States. Consistent and homogenous application of the rules...should be ensured throughout the Union." Recital 13 further notes the need to avoid "a serious risk of circumvention" that could arise from legal fragmentation.

2. European Commission, "Types of EU law": "Regulations are binding legislative acts. They must be applied in their entirety across the EU... A directive sets out a goal that all EU countries must achieve. However, it is up to the individual countries to devise their own laws on how to reach these goals." This official source distinguishes the legal effect of a Regulation from a Directive, highlighting the former's role in creating uniform law.

3. Kuner, C., Bygrave, L. A., & Docksey, C. (2020). The EU General Data Protection Regulation (GDPR): A Commentary. Oxford University Press. In Chapter 1, Section 1.34, the authors state, "The most important feature of the GDPR is that it is an EU regulation, meaning that it is directly applicable in the law of all EU Member States... This is intended to lead to greater harmonisation of data protection law in the EU than was the case under the Data Protection Directive."

4. De Hert, P., & Papakonstantinou, V. (2016). The new General Data Protection Regulation: Still a sound system for the protection of individuals? Computer Law & Security Review, 32(2), 179–194. In Section 2, the article discusses the rationale for the GDPR, noting, "The choice for a Regulation is the most important element of the reform as it aims to put an end to the fragmentation of the data protection framework in the Union." (DOI: https://doi.org/10.1016/j.clsr.2016.02.006)