Dropdown menus have white backgrounds and black text to ensure that they are legible. If you wish to change the color of either the background or the text you can do so with a little custom CSS.
To do so go to the Style tab and scroll to the bottom of the survey preview to access the link to the HTML/CSS Editor. Paste one or both of the below CSS codes on the Custom CSS tab. After "background-color:" and "color:" place either with the color of your choice, such as "black," "purple," etc., or you can use a color picker like this one to insert a hex code: www.colorpicker.com.
To change the color of the background:
To change the color of the text: