DNA helicase - unzips the DNA double helix
DNA Polymerase - edits genes to ensure there are no errors, a 'proofreading system'.
DNA ligase - joins all the DNA together
There will be more acid particles to interact with the limestone at higher concentrations hence the rate of reaction increases.
The question is incomplete but I will try to help you the much I can. If you have carried out the experiment properly, you will notice that the rate of reaction increases as the concentration of the acid increases.
This is because, if the amount of limestone is held constant and the concentration of acid is increased, there will be more acid particles to interact with the limestone at higher concentrations hence the reaction proceeds faster.
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D. membrane bounded organelles
Since you are trying to investigate the possible variables that contribute to reef threats, it is advisable that you do an environmental study between two reefs that have characteristics that are similar or are closely similar. With this, you will be able to identify which is the primary cause of reef threats. Thus the correct answer is B.