**Core Concept:** Magistrates can authorize autopsies in cases where there is suspicion of unlawful act, natural calamity, or accident. In this context, the suspicious circumstances surrounding the woman's death and the dowry related tension could be considered as a "unlawful act".

**Why the Correct Answer is Right:** Magistrates have the power to authorize autopsies when there is a suspicion of a crime or suspicious death. In this case, the woman's death occurred under suspicious circumstances, involving dowry-related tension, which can be categorized as an "unlawful act". Performing an autopsy helps to establish the cause of death and could potentially lead to justice for the deceased.

**Why Each Wrong Option is Incorrect:**

A. **Section 138 of the Indian Penal Code (IPC):** This section deals with the crime of demanding excessive dowry, not ordering an autopsy.
B. **Section 174 CrPC:** This section pertains to the investigation of deaths in certain circumstances, but not specifically related to autopsies in cases of suspicious deaths.
C. **Section 304 B IPC (Death due to cruelty):** This section deals with deaths resulting from cruelty, not ordering an autopsy.
D. **Section 174 CrPC (Investigation of certain deaths):** This section focuses on investigating certain types of deaths, but does not explicitly pertain to autopsies in cases of suspicious deaths.

**Clinical Pearl:** Autopsies are crucial in cases of suspicious deaths, as they help determine the cause of death and can potentially provide justice for the deceased. While the law allows magistrates to authorize autopsies, the correct answer is based on the specific situation described, where the death was under suspicious circumstances involving dowry-related tension, which can be considered an "unlawful act".

**Correct Answer: Section 174 CrPC (Investigation of certain deaths)**

A magistrate has the power to order an autopsy when there is suspicion of a crime or suspicious death, as in this case, where the death occurred under dowry-related tension, which can be considered an "unlawful act". Autopsy results can contribute to establishing the cause of death, which is essential for the deceased's family to seek justice and to prevent similar tragedies from happening in the future.