Your answer would be the last option, c = √(E/m).
We can see this when we rearrange the equation, as:
E = mc²
÷ m
E/m = c²
√
√(E/m) = c
So you got all the steps in rearranging correct :)
I hope this helps!
Answer:

Step-by-step explanation:
All you have to di is subtract the exponents.
Slope intercept is x=3, y=-3. Hope this helped!