Which of the Following Reactions Gives a Positive Value for the Electron

Multiple Choice

Which of the following reactions gives a positive value for the electron affinity?

A) S^-(g) + e^- → S^2-(g)
B) O(g) + e^- → O^-(g)
C) S(g) + e^- → S^-(g)
D) Br(g) + e^- → Br^-(g)