A client complains of a burning sensation in her eyes, but is otherwise feeling fine. When cleaning ...

A client complains of a burning sensation in her eyes, but is otherwise feeling fine.
  When cleaning the room, the nurse senses a pungent smell in the room.
 
  The nurse feels
  that the burning sensation experienced by the client could be a result of some irritating
  or harmful chemical agent and immediately changes the client's room. Which sense of
  observation has the nurse used to identify the problem and take the relevant
  intervention?
  A) Olfactory observation
  B) Auditory observation
  C) Tactile observation
  D) Visual observation