Answer:
The correct option is (B).
Step-by-step explanation:
In case of a blind experiment the participants are divided into groups: one is the treatment group and the other is a control group.
The treatment group are provided with the treatment whereas the control group is not provided with the treatment instead they are given placebos.
To keep the experiment bias free the participants are not informed of the group they belong.
In this case an experiment is conducted to determine the effect of music on studying.
One groups studies with music whereas the other studies without music.
But here the students know which group they belong as they can hear the music playing in the background. This effects the results of the experiment.
Thus, the experiment is not blind.
The correct option is (B).