The hittites are best known for their development of this technology. iron bronze steel copper

Iron is the correct answer.

Explanation:

The Hittites are known for developing the techniques for iron usage around 1500 BC.  Earlier they were using Bronze. Bronze is harder than Iron, The Hittites started to Use Iron weapons which gave them an edge over its rivals and forming the Hittite empire.  When the Hittite empire fell the iron smiths migrated to other places and disseminated the knowledge of  ironwork. The Hittites were made up of several Indo-European speaking tribes. They occupied Anatolia in 17th century BC. They embarked on successful military campaigns due to the use of iron weapons and chariots.

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- "following the american civil war and abolition of slavery, the united states entered a period known as reconstruction, during which black americans continued to suffer from disenfranchisement, racial segregation, and economic oppression. beginning in the early 1950's, black americans launched a series of major campaigns of civil resistance, emphasizing the need for nonviolent protests and civil disobedience."

"such as the montgomery bus boycott of 1955-56, a campaign launched by rosa parks against the policy of racial segregation of the public transit system in alabama. “sit-ins” became popular across the american south, particularly in greensboro, north carolina, increase national sentiment."

- "the counterculture movement"

- "counterculture began to develop in the united states following the rise of conformity in american culture during the 1950s. by 1963, youth, particularly those of the white middle class, began rejecting the cultural standards and normality of their parents, opting for progressive attitudes instead. the movement gained momentum as the civil rights movement became increasingly successful and as the u.s. military intervention of vietnam began to take a negative turn."

"hippie counterculture moved further into popular culture following the summer of love in 1967 when thousands of people came together in the haight-ashbury neighborhood of san francisco. along with greenwich village in new york city, haight-ashbury became a hub for the counterculture movement."