Using a Macrophage‐like Cell Line, Researchers Infected One Set of Petri

Using a macrophage‐like cell line, researchers infected one set of petri dishes with wild‐type Listeria, and, as anegative control, infected another set with a Listeria mutant that was unable to enter cells. At specific time points, the cells were fixed and prepared for electron microscopy. Two hours after infection, they observed that the wild‐type Listeria in the cytoplasmwere surrounded by ______________.

A) a cloud of tubulin
B) a cloud of actin
C) a cloud of keratin
D) agrowth cone
E) comet tails of actin filaments