Why is Switzerland unable to join European Union ( EU) till datae (2010) despite its government persistent effort to so ?

Options

A. 1 Few EU countries like France and Germany are opposed to Switzerland's joining the Union
B. 2 The swiss people continue to vote against joining the EU as they do not want to lose Switerzland's sovereignty
C. 3 EU rejected Switzerland application did not agree to use Euro as currency
D. 4 All of the above