Sara is 33 years younger than Rolando. The Sum of their ages is 105. Select the system of equations if Sara's age is represented by S and Rolando's age is represented by R.

A. s+r=33
s=r-105

B. s+r=105
r=s-33

C. s+r=105
s=r-105

D. s+r=105
s=r-33

E. None of these