Final answer:
A positive response to Lactulose treatment in the context of hepatic encephalopathy is most directly associated with improved cognitive function, seen as clarity of thinking. While mood stabilization and better sleep may occur, these are secondary effects.
Step-by-step explanation:
The evaluation of a patient with a positive response to Lactulose primarily pertains to its use in treating hepatic encephalopathy, a condition associated with liver dysfunction. An effective response to Lactulose in this context would largely be characterized by clarity of thinking, due to the reduction in systemic toxins like ammonia that can impair cognitive functions. While stable mood and improved sleep patterns could also be observed improvements, they are secondary to the cognitive effects and may not be as directly affected by Lactulose treatment. Therefore, the most apparent sign of a positive response to Lactulose would be improved cognitive function. The other options presented such as increased minute respiration, decreased intestinal peristalsis, decreased aldosterone secretion, and increased blood volume do not directly relate to the administration of Lactulose.