Three point charges \[+q,-2q\] and \[+q\] are placed at points \[(x=0,y=a,z=0),\] \[(x=0,y=0,z=0)\] and \[(x=a,y=0,z=0),\] respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are: [AIPMT (S) 2007]

• A. \[\sqrt{2}\,qa\] along \[+y\] direction        
• B. \[\sqrt{2}\,qa\] along the line joining points \[(x=0,y=0,z=0)\]         and       \[(x=a,y=a,z=0)\]
• C. \[qa\] along the line joining points \[(x=0,y=0,z=0)\]           and       \[(x=a,y=a,z=0)\]
• D. \[\sqrt{2}\,qa\] along \[+x\] direction