Concept:
This question requires a chronological understanding of major international diplomatic milestones and the formation of regional organizations throughout the 20th and early 21st centuries.
Step 1: The Post-Colonial Era.
The earliest event is the Bandung Conference (B) held in 1955. This was a large-scale meeting of newly independent Asian and African states, which served as a precursor to the Non-Aligned Movement.
Step 2: Cold War Regionalism.
As the Cold War progressed, regional blocs began to form. ASEAN (D) was established in 1967 with the signing of the Bangkok Declaration. Much later, in South Asia, SAARC (C) was formed in 1985 to promote economic and regional integration among its member states.
Step 3: European Integration and Beyond.
The Maastricht Treaty (A) was signed in 1992, officially creating the European Union and paving the way for the Euro currency. Finally, the most recent contemporary event is Brexit (E), referring to the process of the United Kingdom leaving the EU, which was triggered by a referendum in 2016 and officially completed in early 2020.
Step 4: Final Sequential Order.
Sorting these by year: B (1955) $\rightarrow$ D (1967) $\rightarrow$ C (1985) $\rightarrow$ A (1992) $\rightarrow$ E (2020). This sequence corresponds to Option (3).