If he is going with the descriptive investigation approach, everything will mostly be done qualitatively. This approach does not focus on the conclusive result of the study. Instead, it focuses on the detailed path to get to an effective analytical tools, approach or methodolody towards the conclusion.
Thus, with descriptive investigation, you could trim out unnecessary approaches and single out the effective ones. In this way, you will maximize your resources in a short period of time. Thus, the answer is choice A.
Let us dissect each sentence to tell which of these does not follow the rules for subject-verb agreement.
A.) The subject is 'each of the students' while the verb is 'is'. More particularly, the verb refers to 'each' which is singular. So, this is correct.
B.) The subject is 'student' while the verb is 'were'. The word 'were' is the paste tense of are which is used for a plural subject. But since student is singular, then the verb should have been 'was'. So, this is incorrect.
C.) The subject is 'my dog and my cat' which pertains to two nouns, thus it is plural. It agrees with its plural verb 'are'.
D.) The subject is 'Tom' while the verb is 'does'. Both are intended for singular use. So, this is correct.
Therefore, the answer to this is letter B.
