Esma is creating a brochure for an office tour. She plans to use headings like "Day 1" to differentiate the events planned on different days. She also uses bullets to list the plan for each day. According to Charles Kostelnick's levels of design, Esma's choices belong to the __________ of design.

a. intra-level

b. inter-level

c. supra-level

d. extra-level

e. outer-level