I see = I understand. Perhaps think of it as "I see (the truth in that)"?

i see means i understand

Its a term used to describe that you understand the question or situation

Hi, here person B is agreeing with person A, if it is said in a neutral tone. It all depends on the tone of voice. If person B spoke in a sarcastic tone, then 'I see' would indicate disapproval of person A.

Tones can make a lot difference here. I agree with the first kind lady!