You are required to justify the need to implement a three-tier campus network. Which justification below makes sense for a three-tier campus network?

a. Ability to embed the functionalities of core and distribution into a single layer
b. Makes sense to implement in small-sized networks
c. Ability to effectively implement access security policies to meet business needs
d. Scalable solution for an enterprise environment
e. Makes sense to implement in medium-sized networks only