Answer:
D. Logic is easily understood.
Step-by-step explanation:
Abstract noun illustrates intangible things which may include an idea, state, feeling or quality as contrary to the concrete noun. It exemplifies the objects that do not exist in physical or material state that can only be experienced through senses. Thus, the "logic" in the last option displays this quality as it is an abstract feature while the other options employ the concrete noun as they have a material state.