Which of the following is not considered a continent?

a.) europe

b.) antarctica

c.) africa

d.) india

Answerdistinguish between the mercalli scale and the richter scale;

Idont know i wonder tthough seems like it will be intristing

1. why do astronomers think that there may be other advanced civilizations?
because  it was discovered that there are other planets like earth out there, able to  accommodate life forms.
2. what technologies are astronomers using to look for life on other planets? why?  
they  have used radio telescopes, but now they use laser telescopes   to track laser communications.