The correct option is A.
Multiple trial of an experiment normally improve the reliability of the experiment. Repeating an experiment several time using the same procedure usually increase the accuracy of the data obtained. The average of these data can then be calculated to obtain as near accurate result as possible.
Bacteria play important roles in the global ecosystem.
The ecosystem, both on land and in the water, depends heavily upon the activity of bacteria. The cycling of nutrients such as carbon, nitrogen, and sulfur is completed by their ceaseless labor.
Explanation:
To raise the temperature of the flight muscles high enough to enable flight the bumblebee shivers, rather the same a we do when we are cold. This can easily be seen in a grounded bee as her abdomen will pump to ventilate the flight muscles.