美国商业银行在紧急情况下向美联储申请贷款，美联储收取的利率是( )。

A．贴现率

B．优惠利率

C．短债收益率

D．联邦基金利率

For centuries animals have been used as surrogates for people in experiments to assess the effects of therapeutic and other agents that may be later used for humans.

A. which may later be used fr humans
B. that may be later used in humans
C. which might later be used for humans
D. that might later be used in humans