The four basic tastes are all related to acids and bases in some manner. The taste sensation with the least direct, least well understood, and probably most complex relationship between taste response and acid/base properties is:.
A) bitter.
B) sour.
C) salt.
D) sweet

D. Sweet

Explanation:

The four common tastes include sweet, salt, bitter and sour. The tongue which contains taste buds responsible for taste.

The sweet taste however is found to be the least direct, least well understood, and probably most complex relationship between taste response and acid/base.