What is the correct answer?

[Gaurav]

First you need to make your question clear. what kind of unethical practices was applied to that site? is it on page or off page
if you want to continue with the same site then the correct answer is b but you must know which penalty Google apply to your site. if this penalty is related to content then you need to change it and if this penalty is related to link building then you need to remove such links to make your site good in the eyes of search engines.