Tính tổng S=1/2018.(C 2018 1)^2+2/2017.(C 2018 2)^2

A. $S=\frac{1}{2018}{C}_{4036}^{2018}$

B. $S=\frac{1}{2018}{C}_{4036}^{2019}$

C. $S=\frac{2018}{2019}{C}_{2018}^{1009}$

D. $S=\frac{2018}{2019}{C}_{4036}^{1008}$