Final answer:
The college student is explaining their roommate's behavior through external attribution by considering the roommate's exhaustion from work as the reason for not cleaning the dishes, rather than an internal, dispositional cause.
Step-by-step explanation:
The student is explaining their roommate's behavior through B. external attribution. This is because the student is attributing the roommate's failure to clean the dishes to circumstances outside the roommate's control (exhaustion after a busy day at work) rather than an internal disposition (like laziness or a lack of responsibility). This contrasts with an internal attribution, which would suggest the roommate didn't clean due to personal qualities.
When people explain their own behavior, they often have access to more information about their situation and thus, are likely to provide a situational explanation. This is part of what is known as the actor-observer bias. Conversely, when observing others, people tend to underestimate the influence of the situation due to limited information, leading to a dispositional explanation which is a tendency known as the fundamental attribution error.
The concept of the bystander effect, which is another phenomenon entirely, refers to people's lessened tendency to help in emergencies when there are other witnesses present. This is often attributed to diffusion of responsibility, where the responsibility to act is perceived to be shared among all witnesses.