Plz asap im on the test now which sample is biased? a. interviews of random teenagers who attended a rock concert to find out which musician teens enjoy most. b. a poll randomly surveying half of the students in grade 7 to find out which seventh-grade teacher at the school is most liked. c. an online survey by a game development company taken after the game closes to find out which features of a new game players liked the most. d. a questionnaire delivered to two employees from every department of an office to find out whether employees like the new coffee machine.