Choose the most appropriate option for each gap from the options provided.
It is the business of scientist to accumulate knowledge about the universe and all of that is in it, and to find, if he is able common __6__ which underlie and account for the facts that he knows.
He chooses when he can, the method of the controlled __7__ if he wants to find the effect of light in growing plants, he takes many plants, as like as possible. Some in the dark and all the time keeping all other__8 _ (temperature, moisture, nourishment) the same. In this way, by the light only, the effect of light in plant can be clearly seen.
This __10__ of using ‘controls’ can be apply of a variety of situations, and can be used to find the answers to questions are widely different as possible.
A. experiment B. instruments C. approaches D. factors
