The correct option is C -1
The additive inverse of any number is that number which when added to the given number gives zero.
For any integer a, a + (-a) = 0
So, additive inverse of a is -a = a × (-1)
Multiplication of any number by -1 gives additive inverse of that number.
Example:
Consider number 2. Additive inverse of 2 is -2 and 2 × (-1) = -2