C-12-Q056mediumsingle_mcqABCD is a parallelogram with diagonals AC and BD. AC⃗=\vec{AC}=AC=aAD⃗−AB⃗\vec{AD}-\vec{AB}AD−ABbAD⃗+AB⃗\vec{AD}+\vec{AB}AD+ABcAB⃗−AD⃗\vec{AB}-\vec{AD}AB−ADd−AD⃗−AB⃗-\vec{AD}-\vec{AB}−AD−AB