Can someone help me answer these?

Imagine you know from previous experiments that a particular plant extract kills cervical cancer cells. In a later experiment you use the MTT assay to test the hypothesis: the VSV virus will kill cervical cancer cells. Which of the following would be the positive control sample in the later experiment? Select one: a. The cancer cells that received no treatment b The cancer cells that received plant extract c. The cancer cells that received virus d. The cancer cells that received both virus and plant extract e. There is not enough information to answer this question Imagine you know from previous experiments that a particular plant extract kills cervical cancer cells. In a later experiment you use the MTT assay to test the hypothesis: the VSV virus will kill cervical cancer cells. Which of the following would be the experimental group sample in the later experiment? Select one: a. The cancer cells that received no treatment b The cancer cells that received plant extra