The number which is neither positive nor negative is:
A.1
B.5
C.0
D.10

Hint: We need to find that if any of the given options is neither positive nor negative since we know that positive/negative numbers upon addition or subtraction, adds/subtracts their value from the provided number. So, we will need a number that doesn’t change the value of any number upon addition/subtraction.

Complete step by step Answer:
Upon adding 1 to a random real number x(say), the value will become x+1 and upon subtracting 1 from x, it becomes x-1.
There is a change in the value of the number x, therefore, 1 is not the desired number.
Hence, option(A) is incorrect.
Similarly, for option(B), if we add 5 to x, we again get x+5 and upon subtraction, we get x-5 which implies that there will be a change in the value of x.
Therefore, option(B) is not correct.
For option(C), if we add 0 to x, the value will be x+0= x. There is no change in the value of x. similarly, when we subtract 0 from x, the value will be x-0= x. Again, there is no change in the value of x.
Hence, we can say that 0 is neither positive nor negative as it does not alter the value of the given number upon addition/subtraction.
Therefore, option(C) is correct.
For option(D), we see that the value of x becomes x+10 upon addition and x-10 upon subtraction.

Therefore, option(D) is not correct.

Note: In such questions where we are required to prove something, we just check for every option’s righteousness. You should not get confused between non-negative numbers and positive numbers. 0 is non-negative but it is not considered positive.