Which of the Following Is (Are) Example(s) of a Mixed

Which of the following is (are) example(s) of a mixed cost?
I. A building that is used for both manufacturing and sales activities.
II. An employee's compensation, which consists of a flat salary plus a commission.
III. Depreciation that relates to five different machines.
IV. Maintenance cost that must be split between sales and administrative offices.

A) I only.
B) II only.
C) I and III.
D) I, III, and IV.
E) I, II, III, and IV.