Tracebilty matrix

 Please guide me to the question

 

Which of the following BEST describes the purpose of a traceability matrix?
 
A. It Describes how WBS dictionary are traced to work packages, and how work packages are decomposed from delieverables.
 
B. It's used make sure that all of the subplans of the project management plan have been created.
 
C. It helps you understand the source of each requirement and how that requirement was verified in a letter delieverable.
 
D. It's used to trace the source of every change, so that you can keep track of them through the entire control scope process and verify that the change was properly implemented. 
 
 

 The answer should be C i think

 The answer is definitely C, See PMBOK page 111.

Ok mine was also C but in some test it was shown B

 C