Which sentence includes an adjective clause?
a. I left the countryside twelve years ago when my father was transferred to an artillery division in Dalian.
b. Ever since then we have lived in the city.
c. If my aunt were not in Dismount Fort, I might have forgotten that small town where I went to elementary school only for two years in the late 1960s.
d. My aunt comes to visit us every fall, helping Mother prepare our winter clothes and pickle vegetables.

Question

Which sentence includes an adjective clause? 
a. I left the countryside twelve years ago when my father was transferred to an artillery division in Dalian. 
b. Ever since then we have lived in the city. 
c. If my aunt were not in Dismount Fort, I might have forgotten that small town where I went to elementary school only for two years in the late 1960s. 
d. My aunt comes to visit us every fall, helping Mother prepare our winter clothes and pickle vegetables.