Conclusion of the argument: Hence, it is possible to tackle cancer if adaptive immunity can be stimulated through an external mechanism, such as by artificially injecting a stimulating agent.
So what fact do we need to validate this conclusion ? - that after injecting the agent the adaptive immunity is capable enough to fight cancer. Only then we can say that the injecting of agent was productive.
Hence answer: B
So what fact do we need to validate this conclusion ? - that after injecting the agent the adaptive immunity is capable enough to fight cancer. Only then we can say that the injecting of agent was productive.
Hence answer: B