ABCD is a quadrilateral whose diagonals intersect each other at the point O such that OA = OB = OD. If ∠OAB = 50^{\circ}, then find the measures of ∠ODA.

Question

( A ) 50^{\circ}
( B ) 40^{\circ}
( C ) 30^{\circ}
( D ) 45^{\circ}