I will give you more than one , hardness,luster,color,streak,cleavage,fracture.
It would be B because they are just an explanation of what happens during a experiment
I'm not sure but it's probably C because you are treating a health problem.
Answer:
Current
Explanation:
The equation you mentioned is also known as Ohm's law, which can be applied for any circuit containing a battery and one (or more) resistors:

where
V is the voltage
I is the current
R is the resistance
We can re-arrange the equation and rewrite it explicitely for I, the current, to match the equation mentioned in the text of the question, and we have:
