Statement A: Every monomial is a polynomial.
Statement B: Not every polynomial is a monomial.
Both statement A and statement B are true.
An algebraic expression with only one term is called a monomial, whereas an algebraic expression with one or more(unlike) terms is called a polynomial.
Hence every monomial is a polynomial.
For example, 4x is a monomial, as well as a polynomial.
Hence statement A is true.
Statement B is also true. We shall see realise this by taking an example.
Consider the polynomial 3x2+x+3. Now, this polynomial has three terms. This is an example of a polynomial which is not a monomial.
In fact, one can find many such examples. Hence statement B, which is, not every polynomial is a monomial, is true.