89. Many antibiotics, especially for viruses and cancer therapy involve inhibition of folic acid reactions, especially because folic acid is essential for _____ (A) synthesis of many amino acids (B) conversion of uracil to thymine for DNA synthesis (C) synthesis of deoxyribose for DNA synthesis (D) All of these reactions above are reasons why inhibitors of folic acid act as antibiotics. (E) None of these reactions explains the reason why inhibitors of folic acid act as antibiotics.