The displacement-time graphs of two particles A and B are straight lines making angles of \[30{}^\circ \] and \[60{}^\circ \] respectively with the time axis. If the velocity of A is \[{{v}_{A}}\] and that of B is \[{{v}_{B}}\], the value of \[{{v}_{A}}/{{v}_{B}}\] is

• A. \[\frac{1}{2}\]              
• B. \[\frac{1}{\sqrt{3}}\]
• C. \[\sqrt{3}\]                    
• D. \[\frac{1}{3}\]