In SAT sentence completion question you may find first or second answer choice the most appropriate word. But remember first two or three choices may be designed to deceive you. These initial choices may be the most appropriate but not the best one. So it is better to look at all given choices to reach correct answer.
Example
The easiest choice may be “determine” as you use this word more often in your class discussion of scientific experiment. But read carefully the sentence. It is about physical laws which do not force bodies to behave in a certain way. Since physical laws do not force bodies, so they cannot determine their behavior. Rather, they can explain or describe their behavior. So correct answer choice is (D)
Remember, any correct choice that comes easily may be the one which has been designed to tempt you into wrong guessing.