$1.$ American depository certificates are $\_\_\_\_\_$:

a$.$ certificates issued by banks backed by savings accounts.

b$.$ certificates issued by banks backed by common stocks of a foreign company.

c$.$ a type of security issued by the U$.$S$.$ Treasury.

d$.$ certificates with requirements for regular deposits.

$2.$ One of the requirements for an American depository receipt $($ADR$)$ that is fully registered with the SEC is that:

a$.$ the foreign company must publish financial statements.

b$.$ the certificates be traded only on the New York Stock Exchange.

c$.$ the ADR must be an unsponsored ADR.

d$.$ the underlying common shares must be certified.