Project schedule management is made up of six management processes including:activity definition, activity sequencing,（  ） , and schedule control by order．
A．a(chǎn)ctivity duration estimating, schedule developing, activity resource estimating
B ．a(chǎn)ctivity resource estimating, activity duration estimating, schedule development
C．schedule developing, activity resource estimating, activity duration estimating
D．a(chǎn)ctivity resource estimating, schedule developing, activity duration estimating