If a2 + b2 + c2 = ab + bc + ca, then the value of a + cb is?

Answer: Option B

$$\begin{array}{rl}& \text{According to the question,}\\ & a^2+b^2+c^2=ab+bc+ca\\ & \text{Put }a=1\\ & b=1\\ & c=1\\ & \therefore a^2+b^2+c^2=ab+bc+ca\\ & \Rightarrow 1^2+1^2+1^2=1\times 1+1\times 1+1\times 1\\ & \Rightarrow 1+1+1=1+1+1\\ & \Rightarrow 3=3\left(\text{Satisfy}\right)\\ & \therefore \frac{a+c}{b}\\ & =\frac{1+1}{1}\\ & =2\end{array}$$