Which of the following terms belongs in a different group? femoral pelvic patellar axillary

The term that does belongs to a different group is Patella
Femoral, pelvic and axillary are veins in the body; The patellar is a tendon attaches the bottom of the kneecap (patella) to the top of the shinbone(tibia). It is a ligament that connects to two different bones, the patella and tibia. Patella bone is attached to the quadriceps muscles by the quadriceps tendon. 

Alinear relationship would look like a straight line on the graph. it could have a positive negative or 0 slope. so it could be a line potentially going in any direction but it must be perfectly straight.