James is the head of the production department of an IT company. There are two teams, taking care of the software and hardware production lines, in the production department. Mary is the leader of the software team, and Kate leads the hardware team. Mary and Kate report to James. They have to manage their team members and resolve conflicts among team members. Mary's level in the management hierarchy is that of a ________.

A) first-line manager

B) top manager

C) middle manager

D) functional manager