Let ABCD be a parallelogram whose diagonals intersect at P and let O be the origin. What is \(\overrightarrow {{\rm{OA}}} + \overrightarrow {{\rm{OB}}} + \overrightarrow {{\rm{OC}}} + \overrightarrow {{\rm{OD}}}\) equal to?

• A. \(2\;\overrightarrow {OP} \)
• B. \(4\;\overrightarrow {OP}\)
• C. \(6\;\overrightarrow {OP} \)
• D. \(8\;\overrightarrow {OP} \)