Answer:
It would be B. i.
Step-by-step explanation:
In math they have "imaginary" numbers that take away a negative, and it is i. And just like if you have x, the number goes into the letter, but it's still there. -1 is not a valid number to square root, and if you input it into a calculator it brings up invalid input. The square root of 1 is 1, so you use i to take away the negative, then you are left with 1i or just i.
