Correct option is C
Given:
x + y = 11, and x, y are whole numbers.
Concept Used:
The expression (-1)+ (-1) depends on the parity (whether the number is even or odd) of x and y.
Solution:
Consider the possible cases for x and y:
If x is even, then (-1) = 1.
If x is odd, then (-1) = -1.
Similarly for y.
Since x + y = 11 (an odd number), one of the numbers must be odd and the other must be even.
Therefore, the expression (-1) + (-1) becomes:
(-1) + (-1)= 1 + (-1) = 0
The value of (-1) + (-1) is 0.