Final answer:
Paul sent Timothy to Thessalonica to strengthen the church according to Biblical accounts outside the provided texts. The reference materials do not directly state who was sent.
Step-by-step explanation:
Paul did not directly send anyone to Thessalonica to strengthen the church in these texts provided. However, the individual in question may be Timothy based on Biblical accounts from other sources. The Book of Acts and Paul's own epistles provide information about his missionary journeys and his efforts to strengthen the early Christian churches. In Paul's first letter to the Thessalonians, he mentions sending Timothy to strengthen and encourage the church in their faith, making it likely that this might be the person referred to in the question, although it is not explicitly stated in the provided reference material.