Concept:To find x when f(x)=3, set the given quadratic expression equal to 3 and solve the resulting quadratic equation.Explanation:Given f(x)=3x2−12x+12 and f(x)=3.So, 3x2−12x+12=3.Subtract 3 from both sides: 3x2−12x+9=0.Divide through by 3: x2−4x+3=0.Factorise: (x−1)(x−3)=0.Therefore, x−1=0 or x−3=0.So, x=1 or x=3.Answer:The values of x are 1 and 3.Correct option: A. 1,3.