Excess Vitamin A

A 26-year-old woman comes to the office because she has recently started to experience hip pain. She is an active runner, but has not changed her exercise routine lately. She has also had blurry vision, and has an upcoming appointment with the optometrist. Her last vision check was last year. She has also noticed peeling skin and hair loss, which she attributed to the cold winter temperatures, but there has been no improvement despite moisturizing and increasing her multivitamin dose. She takes insulin for type 1 diabetes, a daily multivitamin, and several tablets of cod liver oil supplements daily. Excess of which of the following is most likely responsible for this patient's symptoms?