I am Lin Feng. This is a picture of my family: my grandfather, my grandmother, my father, my mother, my sister and I. My grandparents are in Beijing now and we are in Zhejiang. My mother is a teacher and my father is a doctor. My sister and I are middle school students. My sister is in Class 1,Grade 8 and I am in Class2, Grade 7. I have a good friend here. Her name is Zhang Ning. We are in the same  class. Lin Feng's mother is   _  .
a student a teacher a doctor a farmer