Choose the correct sentence which is built from the words and phrases given:
when / Mary / my / we / were / friend / used / she / to / help / is / me / with
/ best / homework / at / who / school
A. Who is she Mary, my best friend, who used to help me with homework when we were at school.
B. When we were at school. She is Mary, my best friend, who used to help me with homework.
C. Who is my best friend, Mary, she used to help me with homework when we were at school.
D. She is Mary, my best friend, who used to help me with homework when we were at school.