The level of aggregate supply in the long-run is not affected a. changes in the capital stock. b. changes in the number of workers. c. changes in the price level. d. changes in technology.

C. Changes in the price level

Explanation:

In the long run only change in capital, change in the amount of labour and technological changes affects the level of aggregate supply because everything in the economy is assumed to be used optimally. Therefore, on a LONG RUN price level does not affect the level of aggregate supply.

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.'