A complex sentence contains one independent clause and at least one dependent clause. Here, in your example, there are two simple independent clauses which you need to merge using a dependent adjectival clause in order to make one complex sentence. Here is how to do it:
The boy <u>who wore a green coat</u><u /> carried his sister home.
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.
