What is the correct sequence of occurrence of the following cities in South-East Asia as one proceeds from south to north? 1. Bangkok 2. Hanoi 3. Jakarta 4. Singapore Select the correct answer using the code given below.

1. (a)4-2-1-3
2. (b)3-2-4-1
3. (c)3-4-1-2
4. (d)4-3-2-1