In many west african countries, women are working together in

industrial occupations
banking and finance
agricultural cooperatives
importing and exporting

Agricultural cooperatives.

Explanation:

In West African countries, most of the women are contributing in agricultural cooperatives. Basically small scale agricultural activities are dominated by female workers. About 50% women are contributing in agricultural field and responsible for about 65%-70% to food production in the area. Usually women are engaged in subsistence farming while male are enraged in cash crops production.  

a and b because with the other three, they simplify to something else.