Answer:
O the bystander effect.
Step-by-step explanation:
In psychology, bystander effect is a theory that explains the unwillingness of a person to render help due to the presence of others. This theory explains that there is every tendency to help a victim in need when others are not there but act contrarily in the presence of others.
This is the case in this question where someone collapsed and laid helplessly on the floor due to difficulty in breathing. People walked past this victim without rendering assistance, however, a young lady who was about to help also walked past when she noticed that others were there and not offering help. This young lady has just portrayed the "BYSTANDER EFFECT".