Final answer:
The term 'bilious' refers to someone being in an irritable or grouchy mood, which makes option 1, grouchy, the correct synonym out of the choices provided. (option 1)
Step-by-step explanation:
The synonym for bilious mood is grouchy. The term 'bilious' often refers to a person showing irritability, crankiness, or a generally unpleasant disposition, which aligns best with the word 'grouchy'. Therefore, option 1, grouchy, is the correct synonym here. Being cantankerous could be seen as a related term, as it implies a difficult, argumentative, and often irritable mood.
However, the most direct synonym given the options would be grouchy since 'pleasant' is clearly the antonym of bilious. In the context of providing a mood description, 'bilious' is used to particularly indicate a negative mood that is so intense it repels others.
Hence, the answer is option 1