Carol and David, two moderate$-$income clients with two young children, want to know how recent legislation affects their use of the child tax credit. You should explain that it: a$.$ makes the $2021$ increased child tax credit permanent. b$.$ modified the credit to only apply to $15\%$ of earned income in excess of $$8,500.$ c$.$ returns the credit to $$2,000$ per qualifying child for $2024.$ d$.$ repeals the child tax credit.