B. Crystalline structure
C. Types of chemical elements
And
D. Amounts of chemical elements
Sour receptors occur primarily along the sides of the tongue and are stimulated mainly by acids. Salt receptors are most common in the tip and upper front portion of the tongue. They are stimulated mainly by inorganic salts. Bitter receptors are located toward the back of the tongue
hopefully this helps but i could be really wrong lol
