'People power' refers to the ability of ordinary or disadvantaged people to challenge the powerful ...

'People power' refers to the ability of ordinary or disadvantaged people to challenge the powerful through determined and skilful action. The successful use of 'people power' occurred when the ________.
a.   people demonstrated against the communist governments of some Eastern European countries in 1989
b.   US senators from small states were able to challenge the majority opinion of the American people
c.   government of china suppressed student-led demands for democratization in 1989
d.   governments failed to agree to firm targets for greenhouse gas emissions in Copenhagen in 2009