Answer: If my brother was picked for the games I would not volunteer for him. I wouldn’t want to for many reasons, 1 He has a higher chance of winning than me, and 2 because he’s annoying.
Kay is volunteering tells me that she loves her sister and wants the best for her. It also tells me that Katniss is a very selfless person that she would put herself in harms way to save someone such as prim.
Hope this helps, and sorry for any grammar or spelling errors.