A particle moves along a straight line such that its displacement at any time \[t\] is given by \[S={{t}^{3}}-6{{t}^{2}}+3t+4\] metres The velocity when the acceleration is zero is [CBSE PMT 1994; JIPMER 2001, 02]

• A.             \[3m{{s}^{-1}}\]     
• B.             \[-12m{{s}^{-1}}\]
• C.             \[42\,m{{s}^{-1}}\]
• D.             \[-9\,m{{s}^{-1}}\]