Each of A, B, C, D, E and F has an exam on a different day of a week starting from Monday and ending on Sunday of the same week. Thursday is the only gap day on which no exam is held. E's exam is on Saturday. The exams of A and F are separated by one day that is the gap day. D's exam is immediately before F but is immediately after C. B's exam is on Sunday. On which day is D's exam held?