Which of the following would help explain why the aggregate demand curve slopes downward? Group of answer choices An unexpectedly low price level raises the real wage, which causes firms to hire fewer workers and produce a smaller quantity of goods and services. A lower price level causes domestic interest rates to rise and the real exchange rate to appreciate, which stimulates spending on net exports. A higher price level increases real wealth, which stimulates spending on consumption. A lower price level reduces the interest rate, which encourages greater spending on investment goods.

A lower price level reduces the interest rate, which encourages greater spending on investment goods.

Explanation:

A lower price level reduces the interest rate, encourages greater spending on investment goods which thus, increases the quantity of goods and services demanded. Conversely, a higher price level raises the interest rate, discourages investment spending, and decreases the quantity of goods and services demanded.

ans.

heterothermic organisms include those organisms that can switch between homeothermic (having body temperature higher than environment) and poikilothermic (having variation in internal body temperature) strategies.

some migratory birds show heterothermy as they decrease their metabolic rate during cold nights to keep their body temperature low. drop in metabolic rate allows increase in production efficiency of birds that reduces the internal body temperature to make it equal to external cold temperature during cold nights.

thus, the correct answer is 'birds allow their temperature drop in order to increase their production efficiency.'