The minimum rate of return that a reasonable investor will accept to acquire an investment (required rate of return) is generally determined by A) the investor's previous investment experience B) the current risk-free rate of return plus the risk premium C) the investor's marginal federal income tax bracket D) the Federal Reserve Board (FRB) through its open-market operations

the answer is 4 : )

hope i out!

24 years, i believe is the correct answer.

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.'