Primarily because of the social security system, retirement at age eventually became almost universal.

The correct answer is 65 years.

Explanation:

Though, it may vary from one country from another for few years (61-67), Retirement, which is the administrative act by which a worker in active, either on his own account or that of others, becomes passive or inactive at work.

Nevertheless, due to the extension of lifespan and life expectancy, the age of retirement is being reviewed in many countries, and could be raise up to 70 years in future years.

did mary wollstonecraft believe was a natural ingredient for women’s happiness?

so you should go with

a. strong

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