During<span> the 1960s the availability of primary sources made historical research and</span>writing<span> possible and the debate became more vigorous. Historians Herbert Feis and Gar Alperovitz raised searching questions about the </span>first use<span> of nuclear weapons and their broader political and diplomatic implications.</span>
In this case the answer B is correct; Iron.
Metalworkers in ancient India were renowned for their skills in creating different types of objects that were of very pure quality and the highest standards. These of course were not that common and not just anyone could obtain or afford such items.
The manufacturing industry is a really important sector in the United States as it helped build the middle class after the second World War. In the early 21st century accounted for 10% of corporate profits. Unfortunately the employment in this sector is estimated to decline in the coming years.
