The use of iron and steel is very much common in most of the infrastructure being built today. The new methods developed for the production of these essential metals have helped hasten and loosen the supply for the demand. By that, buildings have sufficient supply of these metals.
a legally recognized subject or national of a state or commonwealth, either native or naturalized:
"a Polish citizen"
synonyms
subject, national, passport holder, native, taxpayer, ... more
I think b makes the most sense. The press would have most likely helped many Protestants share their works easier, such as Martin Luther with the 95 theses.
