Which is the strongest indication that your friend is going through a depression

Feeling sad and in low spirits all the time, and crying a lot
Having no interest in anything, not getting any pleasure out of life
Feeling anxious all of the time
Having difficulty concentrating or remembering things, plus difficulty in making decisions
Low self-confidence and self-esteem, withdrawing from family and friends
Being more irritable and impatient than usual
Feeling helpless and hopeless
Feeling guilty, as if everything that goes wrong is their fault