Question

The best explanation as to why direct democracy would not work well in the United States is that

voting is not mandatory in the United States.
the use of direct democracy would make debate on issues by individuals too difficult.
Ancient Greece was smaller and less geographically diverse than the United States.
the population of the United States is too large.

Answer 1

the population of the United States is too large.

Direct (pure) democracy works best in small, local communities because it's impractical for millions of people spread across a large, diverse country to vote directly on every policy issue. Representative democracy lets elected officials handle day‑to‑day lawmaking.