Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer: $4 x^{2}-3 x+7$.

(A) The given expression is $4 x^{2}-3 x+7$.
In this expression,the variable is $x$.
The exponents of $x$ in the terms $4 x^{2}$,$-3 x^{1}$,and $7 x^{0}$ are $2, 1,$ and $0$,respectively.
Since all the exponents of the variable $x$ are non-negative integers (whole numbers),the expression $4 x^{2}-3 x+7$ is a polynomial in one variable.