Which of the following probably occurred as the U. S. economy experienced declining real GDP in 1953? Check all that apply. Consumer spending declined. Retail sales declined. Industrial production increased. The unemployment rate increased.

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.'

i think the answer to your question is b. directive

the answerr would be 1