In an interesting experiment, researchers examined the effect of ultrasound on birth weight. Pregnant women participating in the study were randomly assigned to one of
two groups. The first group of women received an ultrasound; the second group did not.
When the subjects’ babies were born, their birth weights were recorded. The women
who received the ultrasounds had heavier babies.

Solution
Comparison:
Random assignment:
Control:
Replication:

Is this a blind experiment? Why or why not?