Birds and their subsongs?

When a white-crowned sparrow sings a subsong,








a.) it apparently compares the template it formed during its sensitive period to its own singing.


b.) it has developed the crystallized song that it will sing for the rest of its life.


c.) it is in the plastic phase when it is creating a new, more elaborate song for the next breeding season.





Thanks to all so much!!

Birds and their subsongs?
Birds are not really my thing, but I'd guess 'A' was the answer because the sensitive period is where the young male memorizes the songs of one or more adult birds. Actual vocal production begins during or soon after the sensitive phase when the male begins subsong.





It's not 'C' because the plastic phase is after the subsong phase, and imitations are often incomplete. It's not 'B' because the crystalized song occurs after the plastic song.