A requirements specification is（  ）.
A．a(chǎn) rough list of things that the proposed software ought to do
B．a(chǎn) precise list of things that the proposed software ought to do
C．a(chǎn) formal list of things that the proposed software must do
D．a(chǎn)n estimate of the resources （time,money,personnel,etc）which will be required to construct the proposed software .