The work of women has been economically vital since prehistory, although their contributions have varied according to the structure, needs, customs, and attitudes of society.

In prehistoric times, women and men participated almost equally in hunting and gathering activities to obtain food. With the development of agricultural communities, women’s work revolved more around the home. As urban centres developed, women sold or traded goods in the marketplace.

From ancient to modern times, four generalizations can be made about women's paid work. Women have worked because of economic necessity; poor women in particular worked outside the home whether they were unmarried or married, and especially if their husbands were unable to sustain the family solely through their own work. Women’s indentured work has often been similar to their work at home. Women have maintained the primary responsibility for raising children, regardless of their paid work. Women have historically been paid less than men and have been allocated lower-status work

Some major changes are now occurring in industrial nations, including the steadily increasing proportion of women in the labor force; decreasing family responsibilities (due to both smaller family size and technological innovation in the home); higher levels of education for women; and more middle and upper-income women working for pay or for job satisfaction. Statistically, they have not yet achieved parity of pay or senior appointments in the workplace in any nation.

Artisans working in their own homes not infrequently used the labor of their families. This custom was so prevalent during the Middle Ages, craft guilds of the period, including some that otherwise excluded women, often admitted to membership the widows of guild members, providing they met professional requirements. Dressmaking and lacemaking guilds were composed exclusively of women.

Gradually, the guilds were replaced by the putting-out system, whereby tools and materials were distributed to workers by merchants; the workers then produced articles on a piecework basis in their homes. During the 18th and early 19th centuries, as the Industrial Revolution developed, the putting-out system slowly declined. Goods that had been produced by hand in the home were manufactured by machine under the factory system. Women competed more with men for some jobs, but were concentrated primarily in textile mills and clothing factories. Manufacturers often favored women employees because of relevant skills and lower wages, and also because early trade union organization tended to occur first among men. Employees in sweatshops were also preponderantly women. The result was to institutionalize systems of low pay, poor working conditions, long hours, and other abuses, which along with child labor presented some of the worst examples of worker exploitation in early industrial capitalism. Minimum wage legislation and other protective laws, when introduced, concentrated particularly on the alleviation of these abuses of working women.

Women workers in business and the professions, the so-called white-collar occupations, suffered less from poor conditions of work and exploitative labor, but were denied equality of pay and opportunity. The growing use of the typewriter and the telephone after the 1870s created two new employment niches for women, as typists and telephonists, but in both fields the result was again to institutionalize a permanent category of low-paid, low-status women’s work.

What are the helmets that surface-supplied divers use today made from, according to the passage? A. glass B. copper C. plastic D. canvas