​Which of the tides have variations in height?​

Correct option is A

Mixed tides are tides that have variations in height: 

• Explanation: A mixed tide is a tidal cycle with two high tides and two low tides of different heights each day. Mixed tides are caused by both semi-diurnal and diurnal oscillations. 
• Mixed tides are commonly found along the west coast of North America, in the Caribbean Sea, and along the southeastern coast of Brazil. 

Other types of tides include:

• Semi-diurnal tide: A tidal pattern with two nearly equal high tides and two nearly equal low tides each day. 
• Diurnal tide; A tidal pattern with one low tide and one high tide each day. 
• Spring tide: Tides with the largest range or amplitude, occurring at new moon and full moon. 
• Neap tide: Tides with the smallest range, occurring at intermediate phases of the moon. 
• The moon's gravitational force is the main cause of tides, but the sun's gravitational force also plays a role.