Removal of the apical ectodermal ridge of a limb bud leads to

A、regenerationoftheentirelimbbudfromunderlyingmesoderm;
B、continueddevelopmentoftheproximalstructures,butnoformationofnewdistalstructures;
C、regenerationofanewapicalridgefromadjacentepidermaltissue;
D、degenerationofthelimbbud