Robert springer woke up in the morning and felt a sense of joy and peace as he got ready for work. at work, though challenges came his way, he tackled them without getting stressed about them. this feeling lasted for several days that week. what is one of the reasons that springer's feeling can be categorized as a mood and not as an emotion?

The reason pringer's feeling can be categorized as a mood and not as an emotion is that:  It is prolonged in nature.
Emotions refers to the core feeling that people experience itself. The mood on the other hand, is the emotion that triggered by a certain circumstance.
From the description above, the emotion that Robert experienced is triggered bt his work environment, so it shall be considered as mood.