The answer to this question would be: <span>b.electromagnetic or weak nuclear
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The electromagnetic force can be repulsive or attractive because it was influenced by the magnetic charge. The same charge (positive with positive) will be repulsive but different charge will be attractive(negative and negative). The gravitational force will always be attractive, not repulsive.
Weak nuclear can do both like electromagnetic force.
The air outside your body because when you tried to hold your breath the pressure builds and forces your body to breath by letting out the air but depending the altitude you are the pressure can change hope this helps
Sorry i cant see that question