**Core Concept**
The parasympathetic nervous system (PNS) is a branch of the autonomic nervous system (ANS) that promotes the "rest and digest" response, opposing the sympathetic nervous system's "fight or flight" response. The PNS is primarily responsible for maintaining homeostasis and regulating various bodily functions such as heart rate, digestion, and pupil size.

**Why the Correct Answer is Right**
Parasympathetic stimulation leads to a decrease in heart rate (bradycardia) due to the release of acetylcholine (ACh) at the sinoatrial (SA) node, which activates muscarinic receptors (M2 subtype). This results in a decrease in the automaticity of the SA node, causing a slower heart rate. Additionally, parasympathetic stimulation causes pupillary constriction (miosis) due to the contraction of the sphincter pupillae muscle, which is innervated by parasympathetic fibers.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because parasympathetic stimulation does not typically cause an increase in blood pressure. Instead, it often leads to a decrease in blood pressure due to vasodilation and decreased cardiac output.
**Option B:** This option is incorrect because parasympathetic stimulation does not typically cause an increase in respiratory rate. Instead, it often leads to a decrease in respiratory rate due to the relaxation of the diaphragm and intercostal muscles.
**Option C:** This option is incorrect because parasympathetic stimulation does not typically cause an increase in body temperature. Instead, it often leads to a decrease in body temperature due to vasodilation and increased sweating.

**Clinical Pearl / High-Yield Fact**
The Edinger-Westphal nucleus is the parasympathetic nucleus that controls pupillary constriction and accommodation of the lens for near vision. It is an important landmark in the pons and is often involved in neuroanatomical exams.

**Correct Answer: C. Decrease in blood pressure and respiratory rate and pupillary constriction.**