π/6 is in quadrant I.
The reference angle of an angle in quadrat I is the same angle (If you add or subtract 2π to the angle n times you get the same angle).
Then, the reference angle or π/6 are:
![\begin{gathered} (\pi)/(6) \\ \\ (\pi)/(6)+2\pi=(\pi+12\pi)/(6)=(13\pi)/(6) \\ \\ (\pi)/(6)+2(2\pi)=(\pi)/(6)+4\pi=(\pi+24\pi)/(6)=(25\pi)/(6) \\ \\ (\pi)/(6)-2\pi=(\pi-12\pi)/(6)=-(11\pi)/(6) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/x5p1sc7gremjrlf176xtahxa9mbtlwzhym.png)
For the given options just 13π/6 is a reference angle for π/6Answer: D