Step 1: Understanding the Concept.
This question checks whether three commonly confused words, pray, prey and prying, are used correctly in three separate sentences. Each word sounds close to the others but carries a different meaning, so the task is to match the word to its own sense in each line.
Step 2: Check statement A.
"Pray" is a verb that means to speak to God or to make an earnest request. In "If you pray with faith, they say, it will be answered," the word is used exactly in that devotional sense. This sentence is correct.
Step 3: Check statement B.
"Prey" is a noun that means a victim of a trick, attack, or hunt. The idiom "fall prey to" means to become a victim of something. "He has fallen a prey to cheats" uses this idiom correctly to say he became a victim of cheats. This sentence is correct.
Step 4: Check statement C.
"Prying" is the present participle of "pry," meaning to inquire too closely into someone else's private affairs. "Prying into the affairs of others is bad" uses the word correctly to describe nosy interference. This sentence is correct.
Final Answer:
All three sentences A, B and C use their underlined word correctly, so the right choice is option (C).
\[ \boxed{\text{A, B and C}} \]