C) The core contains equal amounts of hydrogen and helium
        
             
        
        
        
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. 
 
        
                    
             
        
        
        
Answer:
a) when cells are small the movement of food and waste can be efficiently handled by the cell membrane
Explanation:
Cells need to get their nutrients and waste in and out of their cell membrane every quickly. Cells are hard workers anyway! The other options also don't make much sense. The cell shape doesn't mean much to their function, and size doesn't impact shape. The cell's internal parts (mitochondria, vacuole, etc) don't support the cell membrane, they have their own functions to focus on. Cells don't work together in tissue but they can interact with each other when needed.
 
        
                    
             
        
        
        
It's defined as moderate and patients typically seek medical attention due to the symptoms they're experiencing.