Step 1: Understanding the Concept:
The Orient Express was a famous long-distance passenger train service that operated across Europe, connecting the West to the East.
The primary route ran from Paris to Istanbul, crossing through Central and Eastern Europe.
Step 2: Detailed Explanation:
To arrange these cities from West to East, we must look at their longitudinal positions on the European map:
1. Paris (France): This city serves as the western terminus of the original route.
It is located in Western Europe at approximately \( 2.35^{\circ} \) E longitude.
2. Vienna (Austria): Moving eastward from France through Germany, the train reaches Vienna.
Vienna is the capital of Austria and is situated in Central Europe at approximately \( 16.37^{\circ} \) E longitude.
3. Budapest (Hungary): Further east of Vienna lies Budapest, the capital of Hungary.
It is located at approximately \( 19.04^{\circ} \) E longitude.
4. Istanbul (Turkey): Finally, the route moves through the Balkans to reach Istanbul, the gateway to Asia.
Istanbul is the eastern terminus, located at approximately \( 28.97^{\circ} \) E longitude.
Following the West to East direction (\( \rightarrow \)), the sequence is Paris (2) \( \rightarrow \) Vienna (4) \( \rightarrow \) Budapest (1) \( \rightarrow \) Istanbul (3).
This matches the sequence 2 $-$ 4 $-$ 1 $-$ 3.
Step 3: Final Answer:
Based on longitudinal placement from West to East, the correct sequence of cities on the Orient Express line is 2 $-$ 4 $-$ 1 $-$ 3.
The final answer is (B).