The correct options that define plagiarism are:
- not acknowledging the sources your ideas are built upon.
- Using ideas you have previously published and not referencing yourself.
- representing another person's work — their words and/or ideas — as your own.
The third option, "paraphrasing ideas with explicit acknowledgement of the author," does not constitute plagiarism, as acknowledging the author correctly avoids plagiarism even when paraphrasing.