Hich word in this sentence is an example of a collective noun? a flock of canada geese flew over the barn, honking loudly. a. flock b. loudly c. barn d. canada

i think the answer is c.  

- "the basic difference between keywords and subjects is that subjects (or "subject headings") have been predetermined, while keywords have not. a keyword is an easy place to start because you can use any word that seems to fit your search; this is called "natural language" searching."