Here, "body parts" refers to the whole person. AT: "offered yourselves as slaves to everything that is evil and not pleasing to God" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
Paul is using a question to emphasize that sinning results in nothing good. AT: "You gained nothing by doing those things that now cause you shame." (See: [[rc://en/ta/man/translate/figs-rquestion]])