To determine how much of a circle a 100-degree angle turns through, we can find the fraction of the circle that it represents.
A full circle is 360 degrees. To find the fraction of the circle that corresponds to a 100-degree angle, we can set up the fraction as follows:
\[ \text{Fraction of the circle} = \frac{\text{angle}}{\text{total degrees in a circle}} = \frac{100}{360} \]
This fraction can also be simplified:
\[ \frac{100}{360} = \frac{10}{36} = \frac{5}{18} \]
Thus, the correct answer from the provided options is:
\[ \frac{100}{360} \]