What was crucial to the operations of
railroads

answer: karl marx, max weber, and emile durkheim (the fourth could be considered georg simmel)

explanation:

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.

islamic religious leaders have traditionally been people who, as part of the clerisy, mosque, or government, performed a prominent role within their community or nation. however, in the modern contexts of muslims minorities in non-muslim countries as well as secularised muslim states like turkey, indonesia and bangladesh, religious leadership may take a variety of non-formal shapes.

compared to religious leaders/clerics of the other abrahamic faiths, islamic clergy are said to resemble rabbis and not priests. unlike catholic priests they do not "serve as intermediaries between mankind and god",[1] have "process of ordination",[2] or "sacramental functions",[1] but instead serve as "exemplars, teachers, judges, and community leaders," providing religious rules to the pious on "even the most minor and private" matters.[1]