Which expression is a polynomial in (x) and has degree (0)?

Correct answer: (6y-4)

The degree of a polynomial is normally measured with respect to a specified variable. Here the variable is x, so an expression containing no x is treated as a constant in x. A non-zero constant polynomial has degree 0. This is different from the zero polynomial, whose degree is generally left undefined.

In option B, 6y-4 contains y but no x. If y is regarded as a fixed quantity while considering x, the whole expression is a non-zero constant with respect to x, so its degree in x is 0. Option C contains x and has degree 1, option D has x in a denominator and is not a polynomial, and option A is the zero polynomial. Thus B is the intended answer.