(A) Nose
Olfactory receptors detect smell and are located in the nose.
Source: Chapter 6, Section 6.1 – Animals: Nervous System
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The passage directly states: "gustatory receptors will detect taste while olfactory receptors will detect smell," and lists the nose among the sense organs where receptors are located. "Olfactory" relates to smell → nose. This is a straightforward recall question; just write the option and one supporting line.