In which sentence are all periods used correctly?
a. mr. langan requested a wake-up call for 9: 00 a. m. on saturday.
b. dr. vaughn gave mrs vaughn a pearl necklace for their tenth anniversary.
c. the 5 ft plank was too short and needed to be recut.
d. why was there such noise at 6: 00 am?

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.

- "in the declaration of independence, it is stated that all people have certain rights that can't be taken away. when the government fails to protect these rights, the people have no choice but to remove that government and replace it with a government that will do its job and protect the people's rights."