The correct answer is ข. ศรีวิชัย because ศรีวิชัย (Sri Vijaya) was the ancient kingdom that existed from the 7th to the 13th century in present-day Thailand. During this time, the art and culture of the kingdom flourished, including the creation of the Phra Pathom Chedi, which is the largest stupa in Thailand and one of the oldest Buddhist structures in the world. Therefore, the Phra Pathom Chedi is considered an example of the art and architecture of the Sri Vijaya period.