Answer:
a. vertical mobility
Step-by-step explanation:
Vertical mobility-
Vertical mobility is the movement up or down of a person or a group in a status hierarchy. Vertical mobility is commonly known as social mobility.
In the given case study, the poor youth who spends ample of time in the playground for basketball become outstanding in the sport and then receives scholarship and then lucrative contracts in his career. This shows the movement up in the status hierarchy of the youth which is an example of vertical mobility.