casual freinds cuz you never know if you can truly trust them. your close freinds and personal freinds are ppl u have a very close connection to and most likely trust them enough to share your feelings with if they gained that title. opposit sex type freinds can fall under any of the catagories so that eleminates that option.
if you have close or personal freinds they gained that title cuz YOU trust them so really the answer is casual freinds aka just freinds you talk to but dont really trust enough to tell them ur issues or personal problems
hope this helps (◠‿◠✿)
