Final answer:
The type of mobility described is intragenerational mobility, which refers to changes in a person's social mobility over the course of their lifetime. Hence, option (b) is correct.
Step-by-step explanation:
The type of mobility described in the question is intragenerational mobility. Intragenerational mobility refers to the movement of individuals within their lifetime or career, particularly in terms of socioeconomic status or class. In the context provided, the increased earnings and upward movement on the class ladder for computer technicians represent changes in individual positions during their working lives. This is an example of intragenerational mobility because it reflects changes within a single generation or career span rather than across different generations.
Intergenerational mobility involves changes in social status or class between different generations within a family. Downward mobility refers to a decrease in social or economic status. Structural mobility involves changes in social status due to shifts in the overall structure of society.