What is the difference between primary and supporting activities in the IT Value Chain?

What is the difference between primary and supporting activities in the IT Value Chain?
A . Primary activities are core for the overall business operating model, while the activities of the IT value chain are a supporting activity
B . Primary activities focus on the early stages of the IT lifecycle, while supporting activities focus on the later stages
C . Primary activities are core and vital to the IT function, while supporting activities help ensure its efficiency and effectiveness
D . Primary activities focus on systems design and construction; supporting activities include planning and operations management

Answer: C