Answer: C. so he was obliged to proceed on foot.
Step-by-step explanation: a context clue is a hint that an author gives to help define a difficult or unusual word or phrase. The clue may appear within the same sentence as the word to which it refers or it may follow in the next sentence. There are many kinds of context clues, like definitions, synonyms, antonyms, etc. In the given sentence, the context clue that helps to clarify the meaning sof the word "droshky" is "so he was obliged to proceed on foot" this gives us the idea that a "droshky" is some kind of vehicule (and it is a four-wheeled carriage used in Russia).