Final answer:
The bystander effect implies that an individual is more likely to act in an emergency if they recognize it as an emergency and feel personal responsibility to respond, which is the case when they answer 'yes' to two specific questions: whether it is an emergency and if they need to personally act.
Step-by-step explanation:
According to the bystander effect, an individual is more likely to act in an emergency situation when they answer 'yes' to two key questions: 1) Is this an emergency? and 2) Does the situation require me to personally respond to the situation? Therefore, the correct option is 3) When an individual answers 'yes' to two questions. The bystander effect and the associated diffusion of responsibility suggest that when there are more people present, individuals feel less compelled to take action, assuming that someone else will step in. This tends to decrease the likelihood that any one person will help.
Furthermore, personal acquaintance with the victim and the number of bystanders present can significantly influence whether an individual decides to help. However, this effect can be mitigated when a person recognizes that they are the only one capable of helping, or that immediate action is required, prompting them to intervene.