B: she was lucky

    Incorrect.
She was lucky is an external attribution for a person's behavior.   Actually, this is an external unstable attribution.  Luck is something that is an external cause (external attribution), and it is something that is not constant, even though it may seem like somebody is always lucky.  By definition, luck is not constant (unstable attribution).  For more information see p.80 in Myers, and your 2/15/99 lecture notes.