Select the meaning of the capital word in this sentence: Philippa was upset about the doctor's unwillingness to release her from the hospital for another week, so she demanded that he explain his RATIONALE to her.

The word "RATIOALE" refers to the reasoning or justification behind a decision or action. In the context of the sentence, Philippa is asking the doctor to provide the underlying reasons for his decision to keep her in the hospital for another week. By seeking his rationale, she seeks an explanation that clarifies his thought process and justification for the situation, emphasizing her desire to understand the reasoning behind his unwillingness to release her. This meaning aligns perfectly with the notion of justification, making it the correct choice.