Which Prey Defense Represents a Chemical Defense but Not a Warning

Which prey defense represents a chemical defense but not a warning signal?

A) The chemical spray of a bombardier beetle
B) The rattle of a rattlesnake when it is disturbed
C) Nematocysts stored in the body of an orange sea slug
D) Toxic chemicals in the skin of a bright blue poison dart frog
E) Toxic chemicals in similarly patterned viceroy and monarch butterflies