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.
Answer: cofactors.
Explanation:
Epinephrine, insulin and auxins are cofactors.
Cofactors are non protein substance which activate enzymes activity by increasing the rate of chemical reaction of enzymes. They are organic molecules and they assist in enzyme activity. They exist in performing some reactions the enzymes cannot perform alone.
For example, insulin activate enzyme hexokinase which phosphorylate glucose.
