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 vitamin C of citrus fruits binds to specialized receptors on the plasma membrane of taste cells that trigger a sour taste response.
B) Sugars and vitamin C molecules bind simultaneously to receptors on the taste cells, creating a mix of bitter and sweet that results in the sour taste.
C) Citrus fruits release protons from citric acid) that flow directly into taste cells through H⁺ channels in the plasma membrane.
D) Citric acid amplifies the sour taste of vitamin C when it binds to specialized receptors on the taste cells.