Fastest is o over a hundred knots per hour slowest is from under one knot per hour
The controlled experiments are performed by the scientists, when they want to study the changes in the sample on changing a single variable. So, the correct answer is option (b).
In case, all variables are kept same, no changes would be observed in the experiment sample. A controlled experiment can be performed on living thing as well as non living. But, controlled experiment cannot be performed on the things which are influenced by a lot of variables, as they cannot create realistic results. So, the option (a), (c), and (d) are incorrect.
Phytoplankton contribute positively in the oceanic ecosystem as they are a source of food for oceanic animals. Moreover, they remove carbondioxide from the carbon cycle and utilize it for the process of photosynthesis.
Organisms that obtain energy by eating other organisms are called consumers. They are organisms like animals and fungi.
