धार्मिक पुस्तकों का अध्ययन करो।
Step 1: Identify the sentence type.
This is an imperative sentence (a command). Imperatives in English start with the base verb; subject "you" is understood.
Step 2: Map key words.
"अध्ययन करो" $\rightarrow$ "Study"; \ "धार्मिक पुस्तकों" $\rightarrow$ "religious books" (use adjective religious, not the noun religion).
Step 3: Form the English imperative.
Base verb + object: Study religious books.
Step 4: Eliminate wrong options.
(A) Wrong order and wrong noun ("Religion").
(C) Wrong word order.
(D) "religion books" uses a noun as an adjective unnaturally; standard is "religious books."
मैं एक पत्र लिखने जा रहा हूँ।