When would you use a pie chart instead of a bar graph to display data?

The bar/column chart excels at showing discrete data while comparing one data-point vs. another, while the pie chart is the classic way to show how various parts makes up a whole. Both make it easy to for readers compare values relative to each other.

Explanation:

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.'