If the velocity \[\upsilon \] of a particle moving along a straight line decreases linearly with its displacement S is \[20\,\,m{{s}^{-1}}\] to a value approaching to zero at \[S=30\,m,\] then acceleration of the particle at \[S=15\text{ }m,\] is

• A. \[\frac{2}{3}m{{s}^{-2}}\]
• B. \[-\frac{2}{3}m{{s}^{-2}}\]
• C. \[\frac{20}{3}m{{s}^{-2}}\]
• D. \[-\frac{20}{3}m{{s}^{-2}}\]