A function and its domain

Which graph represents a function whose domain is the set of non-negative real numbers?
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The domain is the set of x-values used in the construction of the graph.
Non-negative x-values would start at x = 0 and move to the right.

A function can be determined with the vertical line test.  That is, if a vertical line is passed through the graph and it hits in more than one point, it is not a function.  In other words, each x-value can match up with only one other y-value.
A.)  is a function whose domain consists of both positive and negative real numbers.
B.)  Is not a function
D.)  is a function whose domain consists of negative real numbers and zero
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C.)  is a function whose domain is the set of non-negative real numbers.

Ask Algebra House
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