Answer: (d)

Explanation:
Statement 1 is correct: Amaravati is situated on the banks of the Krishna River in present-day Andhra Pradesh. It flourished under the Satavahanas and later the Ikshvakus. The Amaravati school developed in the lower Krishna-Godavari region. Most standard art-history texts identify Amaravati as the chief centre of Buddhist art in the lower Krishna valley.

Statement 2 is correct: The Amaravati Mahachaitya was among the largest Buddhist stupas in ancient India. This stupa is described as "second only to the Great Stupa at Sanchi in size." The diameter of Amaravati Stupa was around 50 metres. It had elaborate sculptural railings and drum slabs.

Statement 3 is correct: This is a hallmark feature of the Amaravati School. Key characteristics of Amaravati: Highly dynamic figures, Narrative relief panels, Refined carving in white limestone, Strong Buddhist themes. Influenced later South Indian sculptural traditions, spread through maritime trade and Buddhist networks to Sri Lanka, Regions of Southeast Asia. Archaeological and stylistic evidence confirms this diffusion.