Read the passage from of the wisdom of the ancients.
let us now consider his [cupid’s] attributes. he is described with great elegance as a little child, and a child for ever; for things compounded are larger and are affected by age; whereas the primary seeds of things, or atoms, are minute and remain in perpetual infancy.
most truly also is he represented as naked: for all compounds (to one that considers them rightly) are masked and clothed; and there is nothing properly naked, except the primary particles of things.
bacon lists cupid’s attributes in order to
show that cupid is real.
prove that cupid is a child.
disprove the existence of the atom.
compare them to the features of the atom.

the correct answer is c. he speculates on what might happen at given points in the future in a world without people. alan h. weisman is an american author, professor, and journalist. authors organize their information with a purpose. they present their ideas in an organized way. this is called text structure. weisman uses text structure so as to improve overall comprehension and to prove his points.

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.