On which one of the following grounds, in August 2009, Scottish authorities released to return home Abdel Basset al-Megrahi, a former Libyan agent, jailed for life for the bombing of Pan Am Flight 103 on December 1988 that killed 270 people, most of whom were US nationals?

Options

A. UN requested the Scottish authorities to release him
B. He was dying of cancer
C. Charges against him could not be established in the Scottish Court of Law
D. US granted pardon to him