In a clinical trial, a company that manufactures medication to fight the flu virus tested it on 10 men, ages 20 years to 30 years. All the men in the group had shown symptoms of flu before the test. Out of the 10 subjects, 9 men recovered in three days and the 10th recovered in five days. The company announced that the drug was an effective medicine against the flu virus. Why is this data considered biased? A) The number of people in the trial was too high. B) The drug was tested only on people of a small age group. C) The drug should have been tested on healthy people as well. D) The recovery period was not the same for all people in the group.