Which statement correctly describes an interaction of the respiratory and
circulatory systems?
O A. Oxygen from the lungs travels to the heart in the pulmonary
arteries.
B. Oxygen is carried by white blood cells to the air sacs in the lungs.
C. Oxygen is carried by hemoglobin to the alveoli in the lungs.
D. Oxygen from the lungs travels to the heart in the pulmonary veins.

either A or D im so sorry that i dont know the exact answer but B and C are definitely incorrect

Explanation:

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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the transfer for conduction is the heat transfering from the liquid to the spoon

the transfer for convection is the heat rising from the liquid to the air

the transfer for radiation is the heat going through the sides of the cup and to the air

at least that is what i would do