A rancher wants to investigate the use of artificial selection in his cattle herd. Which of these options is an example of artificial selection?

A. Breed a cow that produces large quantities of milk with a bull that comes from a line of cattle with long lifespans.
B.
Trace the family tree of a chicken that lays many eggs back through several generations.
C.
Separate a population of rabbits and monitor any trait changes over the next few generations.
D.
Choose one individual in a population of sheep to favor with food and shelter and see if it mates more.

answer; ///i do believe that the correct answer is (c) hold atoms together to form compound;

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.