In this course's assignments and projects, the instructor has communicated that CSS in HTML documents:

Question $7$Select one:

a$.$

can be done by either referring to CSS completely contained in a separate file from HTML$,$ or$,$ such can be embedded in a single HTML file

b$.$

must be done by referring to CSS that is completely contained in a separate file from HTML

c$.$

The instructor has not communicated anything about CSS use within or outside of a HTML file