Where would you get a pen if you do not have one?\nOptions:\n- briefcase\n- desk drawer\n- friend's house\n- pocket\n- sidewalk
Please answer and provide answer explanation.
friend's house
One has to borrow a pen if one does not have it.

People tend to borrow stuff from their friends.

One goes to a friend's house if one wants to borrow a pen.

.

So, the final answer is friend's house