The mothers of the plaza de mayo wore white head scarves as

In the midst of the last military dictatorship in Argentina, the mothers of the Plaza de Mayo began marches around the May Pyramid, symbol of freedom. To recognize themselves, they began to use a white headscarf originally made with cloth from the diapers that were used for babies, thus representing the children. That handkerchief became his symbol. The Mothers tried to make known their dramas and thus participated in numerous and popular religious marches in which it was convenient that they could recognize themselves.

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering