MARTHA, WHO IS A PEN PAL OF MINE, IS COMING TO MY HOUSE TOMORROW.A...

15. Martha, who is a pen pal of mine, is coming to my house tomorrow.

A. Martha is coming to my house tomorrow because she is my pen pal.

B. Martha, one of my pen pals, is coming to my house tomorrow.

C. Martha is coming to my house tomorrow although she is my pen pal.

D. Martha is coming to my house tomorrow as a pen pal.