The option that is not a difficulty rating for a ski slope is the Pink Triangle.

Standard ski slope ratings

In North America, common ski slope difficulty symbols are:

  • Green circle (beginner)
  • Blue square (intermediate)
  • Black diamond (advanced)
  • Double black diamond (expert only)

In Europe, ski slopes are typically colored:

  • Green or blue for easier runs
  • Red for advanced
  • Black for expert

None of the widely used systems include a pink triangle as an official difficulty rating, so that is the one that does not belong.