GAUSS7 2012 Problem 20

Chris lies on Fridays, Saturdays and Sundays, but he tells the truth on all other days. Mark lies on Tuesdays, Wednesdays and Thursdays, but he tells the truth on all other days. On what day of the week would they both say: “Tomorrow, I will lie.”?

Answer Choices
A. Monday
B. Thursday
C. Friday
D. Sunday
E. Tuesday