Answer:
a. variety diversity
Step-by-step explanation:
Option B is wrong because generational diversity means that there is a variety in the age — for example, Old generation and the young generation or 19th-century generation and 20th century- generation.
Option C is incorrect because working with many professionals cannot be a disparity diversity.
Option D is wrong again, as it is not a separatory diversity.
When many professionals are working together under a team, it is called a diverse group. That means there is a variety. So, option A is correct.