The displacement \[\times \] of a particle is given by \[x=a{{e}^{-\alpha t}}+b{{e}^{\beta t}}\] with \[a,\,b,\,\alpha \] and \[\beta \] as constants. With increase in time, the associated velocity

• A. increases
• B. decreases
• C. increases and decreases
• D. decreases and increases