Which of the Following Are Disadvantages of Using the Covering

Which of the following are disadvantages of using the covering set MPS technique?
1) Under plans common parts
2) Special bill structure is required
3) Requires retrofitting costs
4) Requires sophistication and experience

A) (3)
B) (2) , (3) , and (4)
C) (1) and (3)
D) (4)