**Core Concept**
The suckling mouse assay is a biological test used to isolate and identify substances that can cause harm to the developing fetus or neonate. This test is particularly useful in identifying teratogenic or abortifacient agents.

**Why the Correct Answer is Right**
The suckling mouse assay involves exposing suckling mice to a substance and observing for any adverse effects on their development, such as growth retardation, malformations, or death. This assay is based on the principle that the developing fetus or neonate is highly sensitive to external influences, and any substance that can cause harm to these individuals is likely to be teratogenic or abortifacient. The assay is often used to identify potential teratogens or abortifacients in the early stages of drug development.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the suckling mouse assay is not used to isolate substances that affect adult physiology.
**Option B:** This option is incorrect because the suckling mouse assay is not used to isolate substances that cause cancer.
**Option C:** This option is incorrect because the suckling mouse assay is not used to isolate substances that affect the central nervous system.

**Clinical Pearl / High-Yield Fact**
The suckling mouse assay is a sensitive and specific test for identifying teratogenic or abortifacient agents, and is often used in conjunction with other tests, such as the rat whole embryo culture assay, to identify potential risks to human fetal development.

**Correct Answer:** D.