Step 1: Understanding the Concept:
Analgesics are drugs that relieve pain without causing unconsciousness. Some come from plants.
Step 2: Key Formula or Approach:
Match each plant with its known active compound.
Step 3: Detailed Explanation:
Wintergreen leaves yield oil of wintergreen, which is methyl salicylate. It is applied on the skin in pain-relief balms and sprays, so it is an analgesic.
Turmeric contains curcumin, known as an antiseptic and anti-inflammatory agent.
Cinnamon gives cinnamaldehyde, used mainly as a flavouring and antimicrobial.
Citrus plants supply vitamin C and citric acid, not an analgesic.
Final Answer:
Wintergreen is the plant from which an analgesic is obtained, option (C).
\[ \boxed{\text{Wintergreen (C)}} \]