What is the percent composition of a mixture of (S)-(+)-2-butanol,[!] D/25 = +13.52º, and (R)-(-)-2-butanol,[!] D/25 = -13.52º, with a specific rotation [!] D/25 = +6.76º?

What is the percent composition of a mixture of (S)-(+)-2-butanol,[!]

1.	What is the percent composition of a mixture of (S)-(+)-2-butanol,[!] D/25 = +13.52º, and (R)-(-)-2-butanol,[!] D/25 = -13.52º, with a specific rotation [!] D/25 = +6.76º?
A.	75%(R) 25%(S)
B.	25%(R) 75%(S)
C.	50%(R) 50%(S)
D.	67%(R) 33%(S)
Answer» C. 50%(R) 50%(S)