Spend most of their time in the
red blood cells; lymphatic system
white blood cells; lymphatic system
white blood cells; circulatory system
platelets; lymphatic system
red blood cells; lymph nodes

First option is correct.

Explanation:

Span of RBC (Red blood cells ) is 120 days.

It means RBC lives in the cell body for about 100-120 days.

So, it spend most of their time in the lymphatic system.

The lymphatic system contains spleen, bone marrow, lymph nodes and thymus.

The key element of lymphatic system is the red bone marrow.

And red blood cells (RBCs) are made in red bone marrow.

After 120 days, they are removed from the cycle of circulation from the lymphatic system.

Hence, Red blood cells spend most of their time in the lymphatic system.

Thus, First option is correct.

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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