How are the DNA strands organized?

A) The strands are parallel to one another. The base pairs are not complementary to one another.
B) The strands are antiparallel. The base pairs are complementary and this allows the formation of hydrogen bonds.
C) The strands are parallel to one another. The base pairs are matched with the exact same base pair throughout it.
D) Some strands are antiparallel and others are parallel. This causes some base pairs to be complementary and others are not complementary.

How are the DNA strands organized?

The strands are anti-parallel. The base pairs are complementary and this allows the formation of hydrogen bonds.

Explanation:

Deoxyribonucleic acid (DNA) runs in anti-parallel strands which allows it to stand in an opposing manner while the base pair are complimentary which allows for formation of hydrogen bond.

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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when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.