Question

Write your answers___black ink

Answer 1

The question asks to fill up the blank with an appropriate preposition. So, let us first learn what a preposition is?  

A preposition helps to establish the relationship in between different words in a single sentence. Prepositions commonly in combination with other words within the structure of a sentence are referred to as prepositional phrases. Moreover, the complete phrase works as a modifier, or say adverb or adjective.

Here however, the answer would be: in/with. ("in" suggests instruction, while "with" suggests function of the ink.)

Now, the complete sentence is represented in the following way.

"Write your answers in/with black ink."

Answer 2

write your answers – blank in