Correct Option: D

unconcerned (Adjective) : not worried or anxious about something; not interested in something
inquisitive(Adjective) : curious; enquiring; asking too many questions; very interested in learning about many different things
inadequate (Adjective) : not enough ; insufficient ; incomplete
immature (Adjective) : not fully developed or grown; behaving in a way that is not sensible and is typical of people who are much younger
uncomfortable (Adjective) : not comfortable