What effect is achieved by the opening sentence of this passage

the correct answer is a. how to make proposal that works.

indeed, the register is quite formal and the tone is especially objective as it avoids the use of the first and second person singular (i, you) and opts instead for the third person plural which is more impersonal and focuses on the data and the argument that is being developed by the author. the formality adds the impression of respectability to the work and the impersonality adds objectivity to it.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.