The four primary tastes are sweet, sour, salty and bitter. A fifth taste called”umami” is

gaining recognition. Umami describes the taste of the amino acid glutamate, which is
found in many proteins. Glutamate attaches to receptors that are present in taste buds.
The attachment of glutamate to receptors in a taste bud causes the sensation of taste
through
a. a resting potential
b. an action potential
c. a threshold potential
d. a refractory potential