Which is read by search engines... stylesheets

Is it the print, screen, or none?

[Llama]

Which is read by search engines
a) The print stylesheet
b) The screen (what visitors see)
c) None

Does it vary among search engines, and if so, what do Google, Yahoo, Lycos, and Altavista see?

[Teknorat]

I'll Lock in C. none please Regis.