Which algebraic expressions are polynomials? check all that apply.

Original
Polynomial is an expression of more than two algebraic terms.
So that makes 2, 3 and 6 polynomials

Edited
1) Binomials are included as polynomials
2) Variable must have power that is at least 1

Ans: 2, 3, 5, 6

(Apology for the mistake)

I made a huge error. The correct answer is 2,3,5,6. 
polynomials can't have root variables. Nor can they be of the form 1/x. They can be monomials and there does not seem to be a restriction on numerical coefficients or numbers without variables

How many groups are there?