Select all of the following statements about meta$-$graphs that are true.

Meta$-$graphs are so named because they were invented by Mark Zuckerberg to model social interactions within the Metaverse.

A source node in the original graph must be associated with a sink node in its meta$-$graph.

Meta$-$graphs must be acyclic.

The meta$-$graph of an undirected graph must have no edges.

Meta$-$graphs must have fewer edges than the graph they describe.

A metagraph with a non$-$empty edge set must have at least one source and one sink.