Well in order for chemical digestion to occur period, a enzyme is needed.
In the mouth this enzyme is amylase
The best answer to the question above would be letter d. The sentence presented which is 'Researchers helped further the biological perspective when they demonstrated that electrical stimulation of the brain could evoke emotional responses in animals.' demonstrates how new discoveries can influence perspectives.
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Objects able to block all the light are called opaque and will form a shadow. ... The closer an object is to the light source, the larger the shadow it casts. This is because an object closer to the source will block a larger area of the light, increasing its shadow size.
Explanation:
