Jonathan Fineberg, Strategies of Being: Art since 1945 is a nice survey of
contemporary art from precursors to Ab Ex through early 1990s. Lots of
images and clear writing style (not jargony or too theoretical, yet still
savvy to current trends)
For more up to date stuff, review the current periodicals, especially Arts
Magazine; Art in America; Flash Art; Artforum. The current Artnews has a
feature on "25 most influencial artists of the century" Their picks are
questionable (as are all of those sorts of lists) but they note a lot of the
contemporary artists who were inspired by others.
A few names to look for (in my opinion): Cindy Sherman, Eric Fischl, Anselm
Kiefer, Lorna Simpson, Carrie Mae Weems, Karen Finley, Barbara Kruger, Jeff
Koons, Matthew Barney, Tim Hawkinson, Mike Kelley. (some 80s and 90s
represented, along with a variety of media and theoretical concerns)
Good luck on your test!