Correct Answer:
A. In
The correct answer is In because it satisfies the idiomatic requirement for specifying a liquid substance used as a permanent marking medium.
- In: This is the correct choice. In English syntax, when referring to the medium or substance used to write (such as ink, pencil, or chalk), the preposition 'in' is mandatory (e.g., 'written in ink'). The preposition 'with' would instead be used if referring to the tangible instrument (e.g., 'written with a pen').
- Incorrect Options:
- Through / Into: These are incorrect. They describe spatial transitions or physical movement passing through a boundary, making them structurally ungrammatical in this context.