In which of the following categories did Charles Sanders Peirce classify the…

Concept. Charles Sanders Peirce built his semiotics on two layers that are easy to confuse. The first layer is the triadic sign relation: every act of signification joins a representamen (the sign vehicle), an object (whatever the sign stands for) and an interpretant (the further sign or effect produced in an interpreter). Those three are the correlates, that is, the constituent parts of any sign relation. The second layer is a classification of signs themselves, and Peirce draws it from the kind of relation a sign bears to its object.

On that second layer Peirce's best-known trichotomy yields three categories of signs:

• Icon — stands for its object through resemblance or a shared quality: a portrait, a scale diagram, an onomatopoeic word.

• Index — stands for its object through an actual existential or causal connection: smoke for fire, a weather-vane for wind direction, a pointing finger.

• Symbol — stands for its object through convention, rule or habit, with no natural likeness or physical link: most words, traffic signals, national flags.

Application. The stem asks which categories Peirce used to classify signs, so only items belonging to the second layer qualify. Indices, icons and symbols are precisely the three members of that trichotomy, so the required set is indices, icons and symbols — items B, C and E of the list.

Cross-check. Placing each listed item on the correct layer confirms the set:

Object and interpretant are correlates of the sign relation rather than kinds of sign, so the categories of signs are indices, icons and symbols, i.e. the set naming B, C and E.

Note. Peirce also gives two other trichotomies — qualisign / sinsign / legisign (by the sign's own nature) and rheme / dicisign / argument (by how the interpretant takes it) — but the icon / index / symbol division is the one standardly meant by 'categories of signs'.