During the Great Depression, thousands of people changed social class unexpectedly, usually in a downward spiral. This event was the impetus for a type of social mobility called mobility.

Structural mobility

Explanation:

In simple words, Whenever societal developments allow a large number of individuals to migrate upward or bottom the economic class hierarchy, this is known as structural movement. Individual improvements are not responsible for structural mobility; rather, it is due to developments in community as a whole.

Thus, from the above we can conclude that the correct answer is structural mobility.

european feudalism was a combination of legal and military customs in medieval europe that flourished between the 9th and 15th centuries. broadly defined, it was a way of structuring society around relationships derived from the holding of land in exchange for service or labour.

japanese feudalism. the era of feudalism in japan took place from the 12th through 19th centuries. during that period local rulers, either powerful families or military warlords, dominated the land, while the emperor was merely a figurehead and not a significant political presence.