This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cell Membrane and transpo protiens, Subject name: Physiology
Tetraethylammonium (TEA) is a blocker of the: 
Select and explain. 
A. Na+ channels, B. K+ channels, C. Chloride channels, D. Ca++ channels
B: K+ channels
Answer: B: K+ channels 
Explanation: Tetraethylammonium (TEA) ion is known to block the K+ channels. It is used sometimes to stop the K+ currents, in order to study the other ionic currents and their effects on membrane potential. Tetrodotoxin (TTX) and saxitoxin (STX) are the blockers of Na+ channels. Niflumic acid is Cl- channel blocker used in scientific research studies.