What algorithm does Audacity uses for their pluck?
Also, what musical instrument is the Pluck from ?
“Pluck” is synthesized in Nyquist (a programming language for audio). It is a Karplus-Strong plucked string oscillator.
You can view the Nuquist code by opening the file pluck.ny in a plain text editor (it is in your Audacity plug-ins folder).
The core of the Nyquist code is a command SND-PLUCK, which is described in the Nyquist manual here: http://www.cs.cmu.edu/~rbd/doc/nyquist/part8.html#index763