Suppose That There Are 10 Billion (10,000,000,000,000) Habitable Planets in Our

Multiple Choice

Suppose that there are 10 billion (10,000,000,000,000) habitable planets in our galaxy, that 1 in 5 habitable planets has life, that 1 in 1000 planets with life has at some point had an intelligent civilization, and that 1 in 1000 civilizations that have ever existed is in existence now. How many civilizations would exist at present?

A) 200,000
B) 2,000,000
C) 20,000
D) 20,000,000