The diagram shows two states of the skin microvasculature, State P and State Q, involved in human thermoregulation.
During exposure to a cold environment, which row in the table correctly describes the primary nervous pathway activated by the hypothalamus, the effector response in the skin arterioles, and the resulting state of the microvasculature?
| Nervous pathway activated | Effector response in arteriole | Resulting state of microvasculature | |
|---|---|---|---|
| A | Sympathetic (increased activity) | Smooth muscle contracts | State P |
| B | Parasympathetic (increased activity) | Smooth muscle contracts | State P |
| C | Sympathetic (decreased activity) | Smooth muscle relaxes | State Q |
| D | Parasympathetic (decreased activity) | Smooth muscle relaxes | State Q |
Row A: Sympathetic (increased activity) →\rightarrow→ Smooth muscle contracts →\rightarrow→ State P
Row B: Parasympathetic (increased activity) →\rightarrow→ Smooth muscle contracts →\rightarrow→ State P
Row C: Sympathetic (decreased activity) →\rightarrow→ Smooth muscle relaxes →\rightarrow→ State Q
Row D: Parasympathetic (decreased activity) →\rightarrow→ Smooth muscle relaxes →\rightarrow→ State Q
