**Core Concept**
The question requires knowledge of the pharmacological agents used to manage premature labor, which is a clinical condition where a fetus is born before the 37th week of gestation. The management of premature labor involves the use of tocolytic agents to relax the uterine muscles and prevent preterm birth.

**Why the Correct Answer is Right**
Magnesium sulfate is a tocolytic agent that is commonly used to arrest premature labor. It works by inhibiting the release of acetylcholine from the motor endplates of the uterine smooth muscle, thereby causing relaxation of the uterine muscles. This action helps to prevent preterm birth and allows for the continuation of the pregnancy. Magnesium sulfate also has a neuroprotective effect and is used to treat eclampsia and severe preeclampsia.

**Why Each Wrong Option is Incorrect**
* **Option A:** Aspirin is an antiplatelet agent that is used to prevent blood clots, but it is not used to arrest premature labor.
* **Option B:** α-Methyl dopa is an antihypertensive agent that is used to treat hypertension, but it is not used to manage premature labor.
* **Option D:** Diazoxide is a vasodilator that is used to treat severe hypertension, but it is not used to arrest premature labor.

**Clinical Pearl / High-Yield Fact**
It is essential to note that magnesium sulfate is a tocolytic agent that should be used under close supervision to prevent potential side effects such as respiratory depression in the fetus.

**Correct Answer:** C. Magnesium sulphate