The correct answer is thesis statement.
A thesis statement is the most important sentence in an essay - in it, you will find the main idea of the essay and why it was written in the first place. The author will briefly summarize his or her motivation and goal for writing the essay in this sentence, which is usually found at the end of the introductory paragraph.
The Petrarchan sonnet divides the 14 lines into two sections which are an eight-line stanza (octave) rhyming ABBAABBA, and a six-line stanza (sestet) rhyming CDCDCD or CDECDE.
The thesis is usually in the introduction