Correct option is AGiven:x+1x=1x + \frac{1}{x} = 1 x+x1=1Formula Used: a3+b3=(a+b)(a2+b2−ab)a^3 + b^3 = (a+b)(a^2 +b^2 - ab)a3+b3=(a+b)(a2+b2−ab) Solution:x+1x=1x + \frac{1}{x} = 1x+x1=1 x2−x+1=0x^2 - x + 1 = 0x2−x+1=0x3+13=(x+1)(x2−x+1)=0x^3 + 1^3 = (x + 1)(x^2 - x + 1) = 0x3+13=(x+1)(x2−x+1)=0x3=−1x^3 = -1x3=−1Then the value x12+x9+x6+x3+1x^{12}+x^9 +x^6 +x^3 +1x12+x9+x6+x3+1Thus, x9(x3+1)+x3(x3+1)+1=1x^9 (x^3 + 1) + x^3 (x^3 + 1) + 1 = 1x9(x3+1)+x3(x3+1)+1=1