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Answer:</h2>
Strand of <u>D. DNA</u> acts a template during replication.
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Explanation:</h2>
DNA replication is the natural procedure of delivering two indistinguishable copies of DNA from one unique DNA particle. DNA replication happens in every single living life form going about as the reason for natural legacy.
During the process of replication, a template is used based upon the information contain by it, new strands are produced. Thus, the old DNA acts as template for replication with help of which new daughter strands are produced.

In humans, the medulla region of the brain is mainly responsible for the regulation process of respiration. It is also called the respiratory rhythm centre. The chemosensitive area located near the respiratory centre sends signals across nerve impulses to alter the rate of expiration to eliminate compounds.