Concept:Citizenship can be legally acquired through certain recognised procedures, such as birth, registration, or naturalisation.
Explanation:Citizenship by registration is a formal legal process in which a person qualifies to become a citizen by applying under the law.
Many constitutions allow people, such as those married to citizens or those of citizen parentage, to become citizens through registration.
Nationalization means government takeover of private companies, so it is not a way to acquire citizenship.
Negotiation is a process of discussion, and a decree is an official order; neither is a standard method of gaining citizenship.
Therefore, among the given options, only registration is a recognised way of acquiring citizenship.
Answer:The correct option is B:
registration.