According to the article, which of these will happen second?
A. Volunteers will hold a cup containing mosquitoes to their arm.
B. Volunteers will be given an experimental malaria vaccine.
C. Scientists will test the blood of volunteers for signs of malaria.
D. Scientists will give volunteers a three-day malaria treatment.
The correct answer is B. Volunteers will be given an experimental malaria vaccine.
Explanation: Typically, in a study involving vaccines and challenges, the administration of the vaccine (B) occurs first, followed by holding the cup containing mosquitoes (A). Therefore, according to the order of events, giving the experimental vaccine happens second. For a more in-depth understanding of the article, you may want to check the extended services page.