Step 1: Understanding the Concept:
The question asks to identify the specific Buddhist text that contains the legend of Emperor Ashoka's redistribution of the Buddha's relics and the construction of 84,000 stupas.
Step 2: Detailed Explanation:
(4) Mahaparinibbana Sutta: This text, part of the Sutta Pitaka, describes the last days of the Buddha, his death (parinibbana), and the initial division of his relics into eight portions among different kings and clans, who then built the first eight stupas.
(1) Ashokavadana: This is a much later Sanskrit text (c. 2nd century CE), part of a larger collection called the Divyavadana. It is not a canonical text but a collection of legends about Ashoka. It is this text that famously narrates the story of how Ashoka, after his conversion to Buddhism, gathered the relics from the original eight stupas, subdivided them into 84,000 portions, and had stupas built over them throughout his vast empire.
(2) Sutta Pitaka and (3) Vinaya Pitaka: These are two of the three 'baskets' (Tripitaka) of the Pali Canon. They contain the Buddha's discourses and the rules for the monastic order, respectively, but not the story of Ashoka's redistribution of relics.
Step 3: Final Answer:
The story of Ashoka building 84,000 stupas over the Buddha's relics is found in the Ashokavadana.