When a person attributes the successful outcomes of his behavior to internal causes and unsuccessful outcomes to external, situational causes, the person most likely has an explanatory style known as:

The answer is self-serving bias.

Explanation:

A self-serving bias takes place when a person believes their own success is due to internal factors, and failure is attributed to external factors. This is believed to be done in order to protect or improve one's self-esteem.

Self-serving biases can be found in many different environments, most commonly in school, the workplace and sports.