One Member of a Couple Is Diagnosed with Trichomoniasis and Treated

One member of a couple is diagnosed with trichomoniasis and treated. Should the other person be treated as well, and if so, why?

A) Yes, if both are treated, the infected partner will be cured more rapidly.
B) Yes, if both are not treated, they will keep passing the infection back and forth.
C) No, if the other person is not infected, there is no reason to treat him or her.
D) No, treating both is only necessary if the infected person has an extremely serious case.
E) It doesn't matter; if one is treated, they will both be cured.