Please read the following excerpt from an essay, and answer the question that follows.

I've never actually met a real live humorist. Well, not in person at any rate. However, one summer, having a lot of time on my hands, I discovered unexpected treasures lurking in the local public library. Among the nuggets I unearthed in those musty stacks was a book by humorist Robert Benchley. To this day I remember one of his quips. He wrote, "There are two kinds of people in this world: those who divide the world into two kinds of people and those who don't." After laughing out loud, I became pensive. I wondered why the quip was so funny. A year or so later, I formed a theory. Humor is based on the unexpected.

In the passage above, the topic sentence and the thesis are one and the same. What makes the last sentence effective as a thesis statement?

A. Specific detail
B. Assertion
C. Simplicity
D. Humor

In the given passage, the speaker remembers how he was greatly impressed by the quips he read in a book. The quip he found funny and effective was by Robert Benchley, who jokes about the two types of people in the world.

Looking at the quip, we the readers are also quite expectant of something that shows a demarcation of these two groups of people. But all this is removed when Benchley states "those who divide the world into two kinds of people and those who don't". This is comic, and makes the speaker as well as us, laugh at it though the result was quite unexpected.

So, in using the last line "Humor is based on the unexpected" as a thesis statement and a topic sentence, the speaker asserts that things like that are what humors people more than the real, common jokes. The assertion that the unexpected is what makes it funny makes the whole thesis statement an effective one for the paper.