A car accelerates from rest at a constant rate \[\alpha \] for some time, after which it decelerates at a constant rate \[\beta \] and comes to rest. If the total time elapsed is t, then the maximum velocity acquired by the car is

• A. \[\left( \frac{{{\alpha }^{2}}+{{\beta }^{2}}}{\alpha \beta } \right)\text{t}\]     
• B. \[\left( \frac{{{\alpha }^{2}}-{{\beta }^{2}}}{\alpha \beta } \right)\]
• C. \[\frac{\left( {{\alpha }^{{}}}+{{\beta }^{{}}} \right)\text{t}}{\alpha \beta }\] 
• D. \[\frac{\alpha \beta \text{t}}{{{\alpha }^{{}}}+{{\beta }^{{}}}}\]