According to the Rules of Validity, Which Terms Must Be $\underline{\quad\quad\quad\quad\quad\quad\quad}$

According to the rules of validity, which terms must be distributed in the unstated premise of the following enthymeme? All chairs are furniture.
$\underline{\quad\quad\quad\quad\quad\quad\quad}$
Some furniture is not comfortable.

A) chairs only
B) furniture only
C) comfortable things only
D) comfortable things and furniture
E) furniture and comfortable things