English grammar (prepositions): choose the correct preposition for an instruction about signing a stamped document Complete the sentence with the most natural and idiomatic preposition in standard English: "Affix a revenue stamp and put your signature ______ it." Choose the option that best completes the sentence.

Given data

• Sentence prompt: “Affix a revenue stamp and put your signature ______ it.”
• Task: Select the correct preposition to complete the instruction.

Concept/Approach
In English, the normal collocation is sign on something (e.g., “sign on the line,” “sign on the stamp”). Other prepositions either change the meaning or sound non-idiomatic in this fixed administrative phrase.

Step-by-step reasoning
• “on it” → means the signature is placed on the surface of the object (the stamp); this matches standard office/legal wording. ✅• “upon it” → archaic/overly formal; sometimes acceptable but not preferred in modern instructions.• “over it” / “across it” → can imply writing across the stamp (sometimes used as a security measure), but the routine, neutral instruction is “on it.”

Common pitfalls

• Choosing “upon” for formality when a clear, modern imperative prefers “on.”
• Reading “over/across” as mandatory cancellation; the question seeks the default collocation.

Final Answer
on