The answer to your question would be that the selected sentence uses the past participle part of the verb. The sentence "he has chosen to sit in front of the bus" is in the present perfect tense.
The present perfect tense is a combination of the present tense and the perfect aspect that is used to express a past event that has present consequences. This verb form is used by combining the present tense of the auxiliary verb have with the past participle of the main verb (has chosen).
