Step 1: Define key terms. The question seeks a legal document that "requires attendance" with a "punishment" for non-compliance.
Step 2: Assess the choices.
(1) Oath: A sworn statement of truthfulness. It doesn't mandate attendance.
(2) Conduct money: Funds provided to a witness for travel expenses to court. It supports attendance but doesn't legally compel it.
(3) Subpoena: A court order mandating a person to appear and testify. Non-compliance leads to penalties like fines or imprisonment. This aligns with the question.
(4) Perjury: Lying under oath, a criminal offense. This is a witness's action, not the summoning document.
Therefore, the correct answer is Subpoena.