The correct answer is D) forming the Delian League
The option that was NOT a reform made by Solon was "forming the Delian League."
Solon (640-560 BCE) was a statesman from Athens, Greece. He restructured the social and political life of Athens, stablishing the first steps of the Athenian democracy. He establishing a supreme court, developed a coin system, and canceled farmers' debts. But he did not form the Delian League. The Delian League was formed in 478 BCE to combat the Persian invasion.
