Which of the following is the correct sequence of the Islands of Indonesia from West to East?

1. A

   Java, Sumatra, Lombok, Bali

   Java, Sumatra, Lombok, Bali starts with Java west of Sumatra, which is geographically false: Sumatra lies west of Java. Bali also lies west of Lombok, so the inner order is wrong as well. This option is not the key.

2. B

   Sumatra, Java, Bali, Lombok

   Sumatra, Java, Bali, Lombok is the west-to-east sequence of these Indonesian islands. Sumatra is the great western island, then Java across the Sunda Strait, then Bali, then Lombok across the Lombok Strait. That is the classic Sunda-arc order used in map questions, so (b) is the official key.

3. C

   Sumatra, Java, Lombok, Bali

   Sumatra, Java, Lombok, Bali puts Lombok west of Bali. Bali lies immediately east of Java and west of Lombok. This option is therefore wrong.

4. D

   Bali, Sumatra, Java, Lombok

   Bali, Sumatra, Java, Lombok starts far too far east and then jumps west to Sumatra. It is not a west-to-east chain. This option is not the key.

Summary. Official key is (b) Sumatra, Java, Bali, Lombok. In the Indonesian archipelago these four islands line up from west to east along the Sunda arc. Sumatra is westernmost, then Java, then Bali, then Lombok. Any code that places Java west of Sumatra or Lombok west of Bali fails. Only (b) is correct.