The correct answer is C. The temperature of the water
Explanation:
In an experiment such as the one described about the speed of snails in water, the manipulated variable is the factor or element that is manipulated on purpose. This means the researcher or researchers slightly change this element to compare how this affects another variable. In this context, the manipulated variable is the temperature of the water because researchers used three different temperatures (cool, room-temperature, and warm), and therefore they manipulated or changed this factor. Moreover, it is expected temperature affects the distance nails move, which is the main variable.
<span>Most organisms, including humans, can't use the free gaseous form of nitrogen found in the air. We need other organisms and natural processes to "fix" nitrogen into a solid form that plants and animals can use. Most of the nitrogen that plants and animals use is made by bacteria.</span>
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C raccoons because they eat a wide variety because they can adapt more easily than other populations
Answer of Q.1. is:
C] Ferns
While, Answer of Q.2 is ;
B] Mollusks