In the Lawsuit Involving the Clinton Administration's Use of Executive

In the lawsuit involving the Clinton administration's use of executive privilege, the Supreme Court ruled that:

A) A president's Secret Service protectors cannot be compelled to testify in a trial involving the president
B) Presidential aides may always invoke executive privilege no matter the circumstances of the request from Congress
C) Presidents cannot invoke executive privilege when facing a criminal investigation started through the impeachment process
D) Presidents cannot invoke executive privilege to delay civil proceedings for actions taken prior to assuming the presidency