Multiple Choice
Probably the MOST difficult factor to estimate in the Drake equation is:
A) R*, the rate at which solar-type stars form in the Galaxy.
B) fp, the fraction of stars that have planets.
C) nₑ, the number of planets per solar system that are Earthlike (suitable for life) .
D) L, the lifetime of a technologically advanced civilization.
Correct Answer:

Verified
Correct Answer:
Verified
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