Here's a pic of the ascorbic acid (vitamin C) molecule.
Label 3 different functional groups
https://www.google.com/search?q=ascorbic+acid&client=ms-android-samsung&source=lnms&prmd=sibvn&tbm=isch&sa=X&ved=0ahUKEwjypYTw-cPNAhXHMSYKHbDWD74Q_AUICCgC&biw=360&bih=512#imgrc=TJ7DxebG7PGEbM%3A
I see the alcohol and ester but I'm not sure about the third one. Please help!