The third and the four choice are similar to each other in the sense
that you *have* to write a cover letter when submitting a resume.
The cover letter doesn't have to be long. I usually organize it as follows:
1st para: what position I am applying for and how did I get to know it.
a few words decribing my background
2nd para: they should consider me as a competent candidate by stressing my
skills and background. To be effective, you need to read the
job description
