I got a C in my evolutionary biology class freshman year. To get my GPA up I had to do really well in all of my other math/science courses which was hard but it's definitely doable. If you don't want to retake it just focus on your other classes. You can always make up for a bad grade or two, I did! Don't worry about it too much, leave it behind and think about what you can do to improve it in the future, good luck!