Answer:
Correct option: c. Double blind.
Explanation:
A double blind experiment is an experiment where the participants are divided into two groups: one is the experimental group and the other is a control group. The participants in the experimental group are provided with a treatment and those in the control group are not provided with the treatment but are given a placebo.
In this experiment neither the researcher nor the participants know to which group a participant is placed.
After the experiment the results for the two groups are compared and the conclusion is hence drawn.
Here the researcher randomly assigned babies to either usual care or to a whole-body cooling group. The experimental group is the cooling group and the control group is the group provided with usual treatment.
Thus, the researchers are conducting a double blind experiment to determine whether reducing body temperature for three days after birth increased the rate of survival without brain damage or not.
Thus, the correct option is (c).