What is the first step to determine the sequence of filling electron configurations of an element? Find the elements location on the periodic table.
Use a diagonal diagram.
Add up all the exponents.
Add up all the coefficients.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.