Answer: performing on math tests, developing good work habits, and studying every night.
Explanation:
The event in the sentence is set in the present but will continue into the future. It would therefore be best to use a Present Continuous Tense for the underlined part to properly describe Cassie's actions as well as to introduce uniformity in the tenses used.
Present continuous tense would require the use of verbs with -ing which is why the best verbs to use are "performing", "developing", and "studying".
When the narrator said "Grandfather believed that a well-rooted tree was the color of money", he meant that the tree gave Grandfather food for him and his family to survive.
