Iron is a cheap metal is an example of

The correct answer is A. A good definition states the essential nature of a thing through genus and differentia. "Iron is a cheap metal" gives an accidental attribute instead. Cheapness is not what makes iron iron. It depends on market price, supply and period, and iron has been costly at times. So the definition rests on an accidental quality, which is the classic case of an accidental definition in logic texts.

• Figurative definition uses metaphor or poetic language, such as calling a lion the king of the forest. The sentence here is literal.
• Synonymous definition explains a term through another word with the same meaning, such as "ambrosia is nectar". No synonym is offered.
• Too narrow definition covers only part of the class, such as "man is a European". The statement does not exclude any iron.

The rules of definition sit in the reasoning part of the syllabus, and the habit of separating essential from accidental features helps in precise Mains answer writing and in policy drafting.

Trap: candidates pick "too narrow" because the sentence picks out a single feature. Ask whether the attribute is essential to the thing. Cheapness is not.