By the World Health Organization's (WHO) Definition, What Does the Third

By the World Health Organization's (WHO) definition, what does the third phase of a pandemic alert mean?

A) The period of time between pandemics when there is no identifiable threat
B) New subtype infection may pose a global threat, with declaration of an outbreak of influenza
C) New subtype infection, exercise caution by monitoring any influenza outbreaks and continually assess related risks to the population
D) New subtype infection, with animal spread only