Hormone Signaling. The glands of the endocrine system secrete hormones directly into the extracellular environment. The hormones then diffuse to the bloodstream via capillaries and are transported to the target cells through the circulatory system.
The microvillus are tiny hair- like membrane that greatly increase the amount of surface area of the cells for better reception. It plays a major role in the tongue that are responsible for sending signals to the brain which then decides the taste of the food particle that is on the tongue.
The long and slender structure gives greater space for absorbing the data and then convert them into signals. Hence the microvillus are the slender projections on the tips of some taste bud cells that extend into the taste pores
I believe the answer is B, although A has as well a very good chance of being correct. But B does support evidence with the chemicals found inside them.