When (S)-2-Bromobutane Undergoes an S_N2 Reaction with CH₃O^-, the Product

When (S) -2-bromobutane undergoes an S_N2 reaction with CH₃O^-, the product is the compound shown below. What is the configuration of the product?

A) S only
B) R only
C) both R and S with more R than S
D) both R and S with more S than R
E) equal amounts of R and S