Final answer:
Mannheim's concept of generational location explains how shared historical and social conditions during formative years create a common perspective among individuals of the same generation, influencing their collective actions.
Step-by-step explanation:
According to Mannheim, the basis for shared action among individuals of the same generation is B) Generational location. This concept suggests that individuals of the same generational cohort, having been shaped by the same historical and social conditions, develop a common perspective which differs from those of other generations. These shared experiences can influence their beliefs, feelings, and their way of acting in the social world. Generational location encompasses cultural and social changes that occur during one's formative years, contributing significantly to the development of generational consciousness, thus fostering shared norms, values, and actions within that cohort.