Which of the following is the best example of clear and concise writing for a résumé?
a.
explored every avenue
b.
last but not least
c.
at this point in time
d.
finally

The correct option is D.
When writing resume or cover letter, one is expected to write concisely and use only the words that are really necessary to pass across the information one has. By doing this, the letter will be quite short and the prospective employer will be tempted to read the whole document instead of just scanning it, since most times employers have many of such letters to go through.
So, in resume writing, instead of writing 'last but not the least' it will be preferable to write 'finally'.