Cho a/b = b/c = c/d. Chọn câu đúng: [(a + b + c)/(b + c + d)]^3 = a/b

A. ${\left(\frac{a+b+c}{b+c+d}\right)}^3=\frac{a}{b}$

B. ${\left(\frac{a+b+c}{b+c+d}\right)}^3=\frac{a}{d}$

C. ${\left(\frac{a+b+c}{b+c+d}\right)}^3=\frac{b}{d}$

D. ${\left(\frac{a+b+c}{b+c+d}\right)}^3=\frac{a}{c}$