To determine how much of a circle a 100-degree angle turns through, we can express the angle as a fraction of the total degrees in a circle. A full circle has 360 degrees.
The fraction of the circle that a 100-degree angle represents is:
\[ \frac{100}{360} \]
Now, let's simplify this fraction:
\[ \frac{100}{360} = \frac{10}{36} = \frac{5}{18} \]
So, the 100-degree angle turns through \(\frac{100}{360}\) of a circle.
From the options given, the correct answer is:
D. 100/360