Which of the following is a polynomial?
As we know that,
A polynomial is an expression having variables and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables
Out of the 4 given options, we have:
and 
are not polynomials as they have negative exponent.
is not a polynomial as it has non integral exponent.
And -4 can be written as -4x0, thus it is a polynomial with integer power.
Thus, -4 is the correct option.
4