Arrange the following compounds in increasing order of boiling point.

Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol

1.  Propan-1-ol, butan-2-ol, butan-1-ol, pentan-1-ol

2.  Propan-1-ol, butan-1-ol, pentan-1-ol ,butan-2-ol

3.  Butan-2-ol,propan-1-ol, butan-1-ol, pentan-1-ol

4.  Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol