Choose the appropriate preposition and fill in the blank:
"How did you get here? Did you come ____ train?"
a) by
b) into
c) on
d) in

Hint: Look at the usage of each of the given propositions.

Complete step by step answer:
In the given question, we have to fill the given blank with the most appropriate preposition. A preposition is a word that is used to link nouns, pronouns and phrases within a sentence.

Here, we have the speaker asking another person if he or she came via a train.

Let us take a look at all the given prepositions and see which is the most appropriate option.

Option ‘B’, into, is used to refer to getting into something and not for asking about the mode of transportation used. Hence, it is incorrect.

Option ‘C’, on, is used to refer to being on top of something, but in this scenario the question is about a mode of transport, for which this is not used. Hence, it is incorrect.

Option ‘D’, in, is used to refer to being present in something. It is incorrect as the question is not whether the other person was in a particular train or not, but if he or she came using a train.

Therefore, the correct answer is option ‘A’, by, as it is used to show how something is done. In this scenario the person came using a train and hence it is apt.

Note: To answer such questions easily, learn a couple of prepositions and their usage thoroughly.