You are quoting from page 49 from William Strunk and E. B. White’s famous book on writing, Elements of Style. Assuming you do not use the author’s names in a phrase leading into the quote (an attribution) write the exact parenthetical citation below:

they fear for their lives

the answer is subjective. i personally agree with the first answer for this question.

if one isn't strictly talking about objects then the correct answer would be 'my eyes' since according to this riddle i am asleep and in order to answer/open the door i need to open my eyes first of all.

however, if one is specifically looking for an object, then the first thing i would open would be the door

hope this !