The u. s. government's immigration act of 1990: a. encouraged entrepreneurs to come to the u. s. through "investor visas."b. established a government program to teach american workers displaced by immigration how to start their own businesses. c. established guidelines to entrepreneurs recruit legal aliens as a source of low-cost labor. d. proposed an exchange program for american and european entrepreneurs to temporarily live internationally in order to open up foreign branches for their businesses.

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.'

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