Darlene owns a pharmaceutical company that is trying to create a new vaccine. During the testing phase, the data showed that the vaccine was able to prevent 99 percent of the patients from contracting the disease. However, many patients complained of headaches and a few patients later developed brain cancer. Even though it did help prevent the disease, why might the FDA hesitate to approve this vaccine for general use? A. Only 99 percent of patients were prevented from contracting the disease. B. It is a new vaccine. C. Pharmaceutical companies are not allowed to develop vaccines. D. Many patients had side effects and some developed brain cancer.