In the Equation: Number of Civilizations =Np × Flife ×

Multiple Choice

In the equation: Number of Civilizations =Np × flife × fcivilization × fnow
What do we mean by fnow?

A) the fraction of planets with civilizations on which the civilizations exist now
B) the fraction of time since the Big Bang represented by the present era
C) the fraction of all species ever to exist that we currently are aware of
D) the fraction of planets in the galaxy on which a civilization could theoretically develop now
E) the fraction of civilizations in the universe that currently are sending messages to us