___________ is neither positive integer nor negative integer.
a.Zero
b.One
c.Two
d.Three

Hint: We know that the set of integers can be divided into positive and negative integers and there is a number that does belong to these two and it's nothing other than zero.

Complete step-by-step answer:
We know that the set of integers Z can be divided as two subsets
They are positive integers and negative integers
There exist a number which does not belong to both negative integers and positive integers
The number is nothing other than zero
Therefore zero is the number which is neither negative nor positive
The correct option is a.

Note: Some other things about zero:
1.The number zero is a whole number
2.The number zero is not a positive number.
3.The number zero is not a negative number, either.
4.The number zero is a neutral number
5.Any number divided by itself equals one, except if that number is zero.
In symbols: 0 ÷ 0 = "not a number"