This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Example of direct chemoreceptors are: 
Select and explain. 
A. Olfactory receptor neuron., B. Taste buds., C. Vomeronasal organ., D. All of the above.
B: Taste buds.
Answer: B: Taste buds. 
Explanation: Chemoreceptor (Chemosensor) is a sensory receptor that transduces a chemical signal into an action potential. There are two main classes of chemosensor.
a) Direct:
Taste buds are direct chemoreceptors. Aqueous chemical compounds come into contact with chemoreceptors in the mouth such as taste buds on the tongue and trigger responses.
b) Distant: 
Olfactory receptor neurons in the olfactory system. The main olfactory epithelium (MOE) and the Vomeronasal organ (VNO) detects odorants and pheromones respectively.