Answer:
C."They are effective against a wide variety of bacteria."
Explanation:
Interferons are a group of related proteins produced by the body cells to stimulate the immune system to respond to viral infections by fighting and inferring with the spread of the viral infection.
Statement C by the nursing student would indicate need for further teaching because, interferons which are produced by various types of cells are effective against a wide variety of viruses and not bacteria. They have also been found to be effective in the treatment of melanomia, ovarian cancer etc, to some extent.