Xyz factory has hired a quality assurance research group to investigate chemical handling by its employees. the workers are concerned that the chemicals are making them ill. the research group conducts a poll of the employees to determine how many times each has been hospitalized over the course of a year. then the research group goes to another plant and asks the same poll questions. the two sets of data are compared. in both factories, few people were hospitalized, so the research group concludes there are no health problems. there are often aspects of research that contain bias, which skews the data. which statement below could explain skewed data that did not result from bias on the part of the research company? a. the factory hired the research group. b. polls are not always valid. c. not everyone who is sick must go to the hospital. d. each factory worker may have handled different materials.