To determine the domain of a set of ordered pairs, we need to identify all the unique first elements in each pair. The domain of a set of ordered pairs \((x, y)\) consists of the values of \(x\).
Let's examine each ordered pair given in the problem:
1. \((-1, 1)\) -> The first element is \(-1\).
2. \((0, -1)\) -> The first element is \(0\).
3. \((5, -11)\) -> The first element is \(5\).
4. \((10, -21)\) -> The first element is \(10\).
Therefore, the domain is the set of these first elements: \(\{-1, 0, 5, 10\}\).
Among the given options, the correct one is:
C. [tex]\(\{-1, 0, 5, 10\}\)[/tex].
