Consider the following compounds:

A. n-Butane

B. 2-Methylbutane

C. n-Pentane

D. 2, 2-Dimethylpropane

The correct decreasing order of their boiling points is:

1. A > B > C > D

2. B > C > D > A

3. C > B > D > A

4. D > C > B > A