Texas Department of Criminal Justice
If you chose C, you are correct.
C. Cannot wear political buttons.
PD-23 (Employee Political Activity and Participation in Employee Organizations) discusses guidelines for running for an elective office. It prohibits the following activities in connection with employee political activity while on agency premises/property: the placement, distribution, display, or wearing of any form of political campaign materials, including but not limited to, buttons, handbills, posters, shirts, hats, and the use of employee bulletin boards.