Which is an example of plagiarism?

not placing quotation marks around a direct quote

not citing a graph or a chart

using another's ideas without giving credit

summarizing another's ideas and citing them

all of the above

a, b, and c only

I feel like it would be all of them but the one that calls out the most would be using another's ideas without giving them credit. Plagiarism is all about not citing or giving credit to the person who wrote the article, letter, essay, etc ... And using it for yourself claiming as though you wrote it yourself.

Not giving someone credit for their own work. you can put quotations on whatever you take, but if you don't properly cite it as their work, then that would be another form of plagiarism.