What is an example of a internal force

Which of the following entries would be made to record the requisition of $12,000 of direct materials and $6,900 of indirect materials? (assume that indirect materials are included in raw materials inventory.) a. manufacturing overhead 18,900 raw materials inventory 18,900 b. wip inventory 12,000 manufacturing overhead 6,900 raw materials inventory 18,900 c. raw materials inventory 18,900 wip inventory 18,900 d. wip inventory 18,900 raw materials inventory 18,900