PQ is a double ordinate of the parabola\[{{y}^{2}}=4ax\]. The locus of the points of trisection of PQ is

• A.            \[9{{y}^{2}}=4ax\]                     
• B.            \[9{{x}^{2}}=4ay\]
• C.            \[9{{y}^{2}}+4ax=0\]                 
• D.            \[9{{x}^{2}}+4ay=0\]