In sewing projects you need to add your own seam and hem and

your word would be isle.

isle is an island or peninsula especially a small one.

if you add the letter "a" you get aisle, which is a passage between 2 rows of something like chairs, shelves, or something else.

a. symbolism

b. opinions

all of them

c. hidden messages

d. political statements

12-bar blues chorus = a a b