It was on Monday, so the answer is A. 
From Monday to Wednesday Mark always lies. For the rest of the week he tells the truth. One day, Mark said to Mary:  $$1$$) "Yesterday I lied." and  $$2$$) "Starting the day after tomorrow, I will be lying for two consecutive days."  On what day of the week did Mark talk to Mary? 

[A] Monday 
[B] Tuesday 
[C] Wednesday 
[D] Thurday 
[E] Friday 