A u se case model is

A、A diagra m wit h s tick-figu re actors connected to u se cases drawn in ovals
B、Text flows of even ts t h a t describe t he s teps a n actor takes to accom plis h t he goal of a u se case
C、A diagra m wit h s tick-figu re actors connected to u se cases drawn in ovals, a n d text flows of even t s t h a t describe t he s teps a n actor takes to accom plis h t he goal of a u se case
D、A diagra m wit h s tick-figu re actors connected to u se cases drawn in ovals, text flow of even t s t h a t describe t he s teps a n actor takes to accom plis h t he goal of a u se
case,
a nd associated docum en ted b u siness r ules affecting t he u se case