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: Physiology
Rheobase indicates: 
Select and explain. 
A. Magnitude of current, B. Rate of discharge, C. Velocity of nerve conduction, D. Specificity of impulse transmission
A: Magnitude of current
Answer: A: Magnitude of current 
Explanation: Rheobase: The minimum strength or magnitude of a stimulus, which is able to produce AP in an excitable tissue (e.g. Nerve,muscle) regardless of the duration it takes.