Each of L, M, N, O, P, Q and R has an exam on a different day of the week starting from Monday and ending on Sunday of the same week. M is the first person to answer the exam. Only two people answer an exam between M and L. P does not answer an exam immediately after M but answers an exam immediately before L. Q answers an exam immediately after L. O is the last person to answer the exam. N does not answer an exam on Saturday. Who answers the exam on Tuesday?
AQ
BL
CP
DN