How Do Citrus Fruits Such as Lemons Cause the Basic

How do citrus fruits such as lemons cause the basic taste of sour?

A) the more acidic the food the more depolarization of the sensory receptor
B) Ascorbic acid binds to sensory receptors on the plasma membrane of taste cells,which leads to the triggering of cellular activity that trigger a sour taste response.
C) Sugars and ascorbic acid bind sensory receptors on the plasma membrane of taste cells,which leads to the triggering of cellular activity that trigger a sour taste response.
D) Citric acid amplifies the sour taste of vitamin C when it binds to specialized receptors on the taste cells.