Pen : Ink :: Pencil : ?

Answer: Option C

Analogy: Pen : Ink :: Pencil : Graphite

In this analogy, we compare two pairs of related items. The relationship between a pen and ink is that ink is the substance used by the pen to write. Similarly, the substance used by a pencil to write is graphite.

Incorrect Options:

Option A: Knife
This option is incorrect because a knife is not related to a pencil in the same way that ink is related to a pen. A knife does not serve as the writing medium for a pencil.

Option B: Write
This option is incorrect because "write" is an action, not a substance. The analogy requires a substance that enables writing, similar to how ink enables a pen to write.

Option D: Chalk
This option is incorrect because chalk is a writing medium on its own and is not related to a pencil. The correct relationship should be between a pencil and its writing substance.

Correct Usage Example:
Pen : Ink :: Pencil : Graphite

This construction accurately represents the analogy by identifying the correct relationship between the items, highlighting that graphite is to a pencil what ink is to a pen.