Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

One of these organisms was the basis of the rII system used by Benzer for single nucleotide mapping,
and the cosmid uses elements derived from one of these organisms. The first stretch of DNA ever
sequenced by Frederick Sanger was from one type of this organism, dubbed phi X, and the Luria-Delbruck
experiment used them to show that mutations are spontaneous. Another experiment using them labeled
their DNA with phosphorus-32 and their proteins with sulfur-35 in order to show that nucleic acids are the
material of heredity; that experiment was performed by Hershey and Chase using the T4 type. For 10
points, name these viruses which infect bacteria.
Science