Which of the following shows 2x3y - 3x2 + 7y2x - 12y written in standard form? . a) 2x3y+7y^2x-3x^2-12y. b) -12y+7y^2x-3x^2+2x^3y. c) 7y^2x-12y+2x^3y-3x^2. d) -12y-3x^2+7y^2x^3y

To write a polynomial in its standard form, arrange the exponents of the variables in decreasing order giving the priority to the first variable that appears in the alphabetical order. So, from the given above, the answer would be
                                2x³y + 7y²x - 3x² - 12y
Thus, the answer is letter A.