The correct answer is - Theory of the Ekman spiral
V. W. Ekman or Vagn Walfrid Ekman was a Swedish physical oceanographer. He is famous for his studies of the dynamics of ocean currents. Ekman developed a theory called as the “theory of the Ekman spiral”. This theory explains maintaining balance between frictional effects in the ocean and the Coriolis force. The force arises from moving objects in a rotating environment such as planetary rotation.