takes the concept of companies having used self-employed consultants to work on individual projects or provide content a step further by enabling people to work in more flexible ways on a variety of Internet-related projects.

E-lancing

Explanation: E-lancing is the process of taking a job through the internet whereby the person is working for oneself rather than an employer and is not necessarily committed to a specific employer long-term. However, some act as an individual who may have the right to prosecute on a contract even though it is not initially an active party to the contract and offers intermediation assistance like paying the freelancer when the job is finished so as to minimize the possibility of not paying.

metallurgy is your answer

the "study of metals and the process of refining ("

note that it says metal. metallurgy has the word "metal" in it, and so is most likely your answer (and is your answer).

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answer: a. the kind of population living in your neighbourhood.

the census explorer data tool by the us census bureau allows the user to zoom in on any neighbourhood within the united states and find the kind of people residing in that by race and age.  

the tool needs to needs to be used twice – once in order to find what type of people reside in a neighbourhood, and then to see the age groups of the people in the same neighbourhood.