Read the paragraph and dictionary entry. When the state council on the arts first announced plans for a new arts center, people in our area immediately showed interest. My neighbor, a city planner, volunteered his time to complete a study. His study showed that our area could support the additional traffic the center would likely create. Since he was instrumental in bringing the arts center to our area, the council honored him with a plaque at the opening night party. Dictionary instrumental (in stroo . mental) adj.
1. relating to an essential influence or agent of action
2. associated with, created for, or performed by musical instruments
3. conducted with, or related to, an instrument or device
4. relating to a philosophy focused on determining the value and helpfulness of ideas

When Curtis first read this paragraph, he thought the word instrumental meant "significant."
Which dictionary entry shows that Curtis's understanding of the word instrumental was correct?
a. entry 1
b. entry 2
c. entry 3
d. entry 4