Final answer:
In Ann Beatty's story "Janus," the object that Foster provides as a sexual symbol in a very nonsexual object is a mirror.
Step-by-step explanation:
In Ann Beatty's story "Janus," Foster provides the example of a mirror as a sexual symbol in a very nonsexual object. The mirror is described as being large and hung above the couch in his apartment. It reflects the entire room, including a woman's body parts cut out from a magazine that Foster has taped to the mirror. This use of a mirror as a sexual symbol suggests Foster's obsession with objectifying women and his desire for control and power.