Final answer:
Cathy is angered by Adam's demeanor and actions/looks toward her, which lack genuine emotion and amusement.
Step-by-step explanation:
Cathy is angered by Adam's demeanor and actions/looks toward her because they lack genuine emotion and root in mirth or amusement. She is disturbed by his scarlet smile, which she perceives as an invitation to a kiss rather than a genuine display of happiness. This causes her to slip into a moody depression and changes the atmosphere between them.