A server can have many definitions, but in this particular case, the answer is A.
Answer: URN(Uniform Resource Name) is the basically a subset of the Uniform Resource identifier(URL). It uses "urn"scheme for the working an implementation. Uniform resource name functions by identifying components uniquely through their name.
The most common example of URN is ISBN (International Standard Book Number)number which helps in the unique searching and identification of book.
A mail server. --------------------------------------------
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<span>C. Get the help of someone with specialized knowledge in the area.</span>
