$25.$ Which statement about ABC analysis is true?

a$)$ ABC analysis is an approach used to compare brands based on input$-$output ratios.

b$)$ ABC analysis is a customer lifetime value approach.

c$)$ ABC analysis is a static $($single$-$period$)$ approach used for brand evaluation.

d$)$ ABC analysis is a dynamic $($multi$-$period$)$ approach to customer valuation.

e$)$ ABC analysis is used to create a hierarchy of customers based on the revenues they generate.